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llvm-project/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

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//===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
// Details of the algorithm:
// http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/InstVisitor.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/SwapByteOrder.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include <algorithm>
#include <iomanip>
#include <limits>
#include <sstream>
#include <string>
#include <system_error>
using namespace llvm;
#define DEBUG_TYPE "asan"
static const uint64_t kDefaultShadowScale = 3;
static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
static const uint64_t kDynamicShadowSentinel = ~(uint64_t)0;
static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
static const uint64_t kPS4CPU_ShadowOffset64 = 1ULL << 40;
static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
// The shadow memory space is dynamically allocated.
static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
static const size_t kMinStackMallocSize = 1 << 6; // 64B
static const size_t kMaxStackMallocSize = 1 << 16; // 64K
static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
static const char *const kAsanModuleCtorName = "asan.module_ctor";
static const char *const kAsanModuleDtorName = "asan.module_dtor";
static const uint64_t kAsanCtorAndDtorPriority = 1;
static const char *const kAsanReportErrorTemplate = "__asan_report_";
static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
static const char *const kAsanUnregisterGlobalsName =
"__asan_unregister_globals";
static const char *const kAsanRegisterImageGlobalsName =
"__asan_register_image_globals";
static const char *const kAsanUnregisterImageGlobalsName =
"__asan_unregister_image_globals";
static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
static const char *const kAsanInitName = "__asan_init";
static const char *const kAsanVersionCheckName =
"__asan_version_mismatch_check_v8";
static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
static const int kMaxAsanStackMallocSizeClass = 10;
static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
static const char *const kAsanGenPrefix = "__asan_gen_";
static const char *const kODRGenPrefix = "__odr_asan_gen_";
static const char *const kSanCovGenPrefix = "__sancov_gen_";
static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
static const char *const kAsanPoisonStackMemoryName =
"__asan_poison_stack_memory";
static const char *const kAsanUnpoisonStackMemoryName =
"__asan_unpoison_stack_memory";
static const char *const kAsanGlobalsRegisteredFlagName =
"__asan_globals_registered";
static const char *const kAsanOptionDetectUseAfterReturn =
"__asan_option_detect_stack_use_after_return";
static const char *const kAsanShadowMemoryDynamicAddress =
"__asan_shadow_memory_dynamic_address";
static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
static const size_t kNumberOfAccessSizes = 5;
static const unsigned kAllocaRzSize = 32;
// Command-line flags.
static cl::opt<bool> ClEnableKasan(
"asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
cl::Hidden, cl::init(false));
static cl::opt<bool> ClRecover(
"asan-recover",
cl::desc("Enable recovery mode (continue-after-error)."),
cl::Hidden, cl::init(false));
// This flag may need to be replaced with -f[no-]asan-reads.
static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
cl::desc("instrument read instructions"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClInstrumentWrites(
"asan-instrument-writes", cl::desc("instrument write instructions"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClInstrumentAtomics(
"asan-instrument-atomics",
cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
cl::init(true));
static cl::opt<bool> ClAlwaysSlowPath(
"asan-always-slow-path",
cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
cl::init(false));
static cl::opt<bool> ClForceDynamicShadow(
"asan-force-dynamic-shadow",
cl::desc("Load shadow address into a local variable for each function"),
cl::Hidden, cl::init(false));
// This flag limits the number of instructions to be instrumented
// in any given BB. Normally, this should be set to unlimited (INT_MAX),
// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
// set it to 10000.
static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
"asan-max-ins-per-bb", cl::init(10000),
cl::desc("maximal number of instructions to instrument in any given BB"),
cl::Hidden);
// This flag may need to be replaced with -f[no]asan-stack.
static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
cl::Hidden, cl::init(true));
static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
"asan-max-inline-poisoning-size",
cl::desc(
"Inline shadow poisoning for blocks up to the given size in bytes."),
cl::Hidden, cl::init(64));
static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
cl::desc("Check stack-use-after-return"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
cl::desc("Check stack-use-after-scope"),
cl::Hidden, cl::init(false));
// This flag may need to be replaced with -f[no]asan-globals.
static cl::opt<bool> ClGlobals("asan-globals",
cl::desc("Handle global objects"), cl::Hidden,
cl::init(true));
static cl::opt<bool> ClInitializers("asan-initialization-order",
cl::desc("Handle C++ initializer order"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClInvalidPointerPairs(
"asan-detect-invalid-pointer-pair",
cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
cl::init(false));
static cl::opt<unsigned> ClRealignStack(
"asan-realign-stack",
cl::desc("Realign stack to the value of this flag (power of two)"),
cl::Hidden, cl::init(32));
static cl::opt<int> ClInstrumentationWithCallsThreshold(
"asan-instrumentation-with-call-threshold",
cl::desc(
"If the function being instrumented contains more than "
"this number of memory accesses, use callbacks instead of "
"inline checks (-1 means never use callbacks)."),
cl::Hidden, cl::init(7000));
static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
"asan-memory-access-callback-prefix",
cl::desc("Prefix for memory access callbacks"), cl::Hidden,
cl::init("__asan_"));
static cl::opt<bool>
ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
cl::desc("instrument dynamic allocas"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClSkipPromotableAllocas(
"asan-skip-promotable-allocas",
cl::desc("Do not instrument promotable allocas"), cl::Hidden,
cl::init(true));
// These flags allow to change the shadow mapping.
// The shadow mapping looks like
// Shadow = (Mem >> scale) + offset
static cl::opt<int> ClMappingScale("asan-mapping-scale",
cl::desc("scale of asan shadow mapping"),
cl::Hidden, cl::init(0));
static cl::opt<unsigned long long> ClMappingOffset(
"asan-mapping-offset",
cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"), cl::Hidden,
cl::init(0));
// Optimization flags. Not user visible, used mostly for testing
// and benchmarking the tool.
static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClOptSameTemp(
"asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClOptGlobals("asan-opt-globals",
cl::desc("Don't instrument scalar globals"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClOptStack(
"asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
cl::Hidden, cl::init(false));
static cl::opt<bool> ClDynamicAllocaStack(
"asan-stack-dynamic-alloca",
cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
cl::init(true));
static cl::opt<uint32_t> ClForceExperiment(
"asan-force-experiment",
cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
cl::init(0));
static cl::opt<bool>
ClUsePrivateAliasForGlobals("asan-use-private-alias",
cl::desc("Use private aliases for global"
" variables"),
cl::Hidden, cl::init(false));
static cl::opt<bool>
ClUseMachOGlobalsSection("asan-globals-live-support",
cl::desc("Use linker features to support dead "
"code stripping of globals "
"(Mach-O only)"),
cl::Hidden, cl::init(true));
// Debug flags.
static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
cl::init(0));
static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
cl::Hidden, cl::init(0));
static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
cl::desc("Debug func"));
static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
cl::Hidden, cl::init(-1));
static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
cl::Hidden, cl::init(-1));
STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
STATISTIC(NumOptimizedAccessesToGlobalVar,
"Number of optimized accesses to global vars");
STATISTIC(NumOptimizedAccessesToStackVar,
"Number of optimized accesses to stack vars");
namespace {
/// Frontend-provided metadata for source location.
struct LocationMetadata {
StringRef Filename;
int LineNo;
int ColumnNo;
LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
bool empty() const { return Filename.empty(); }
void parse(MDNode *MDN) {
assert(MDN->getNumOperands() == 3);
MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
Filename = DIFilename->getString();
LineNo =
mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
ColumnNo =
mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
}
};
/// Frontend-provided metadata for global variables.
class GlobalsMetadata {
public:
struct Entry {
Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
LocationMetadata SourceLoc;
StringRef Name;
bool IsDynInit;
bool IsBlacklisted;
};
GlobalsMetadata() : inited_(false) {}
void reset() {
inited_ = false;
Entries.clear();
}
void init(Module &M) {
assert(!inited_);
inited_ = true;
NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
if (!Globals) return;
for (auto MDN : Globals->operands()) {
// Metadata node contains the global and the fields of "Entry".
assert(MDN->getNumOperands() == 5);
auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
// The optimizer may optimize away a global entirely.
if (!GV) continue;
// We can already have an entry for GV if it was merged with another
// global.
Entry &E = Entries[GV];
if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
E.SourceLoc.parse(Loc);
if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
E.Name = Name->getString();
ConstantInt *IsDynInit =
mdconst::extract<ConstantInt>(MDN->getOperand(3));
E.IsDynInit |= IsDynInit->isOne();
ConstantInt *IsBlacklisted =
mdconst::extract<ConstantInt>(MDN->getOperand(4));
E.IsBlacklisted |= IsBlacklisted->isOne();
}
}
/// Returns metadata entry for a given global.
Entry get(GlobalVariable *G) const {
auto Pos = Entries.find(G);
return (Pos != Entries.end()) ? Pos->second : Entry();
}
private:
bool inited_;
DenseMap<GlobalVariable *, Entry> Entries;
};
/// This struct defines the shadow mapping using the rule:
/// shadow = (mem >> Scale) ADD-or-OR Offset.
struct ShadowMapping {
int Scale;
uint64_t Offset;
bool OrShadowOffset;
};
static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
bool IsKasan) {
bool IsAndroid = TargetTriple.isAndroid();
bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
bool IsFreeBSD = TargetTriple.isOSFreeBSD();
bool IsPS4CPU = TargetTriple.isPS4CPU();
bool IsLinux = TargetTriple.isOSLinux();
bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
TargetTriple.getArch() == llvm::Triple::ppc64le;
bool IsSystemZ = TargetTriple.getArch() == llvm::Triple::systemz;
bool IsX86 = TargetTriple.getArch() == llvm::Triple::x86;
bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
TargetTriple.getArch() == llvm::Triple::mipsel;
bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
TargetTriple.getArch() == llvm::Triple::mips64el;
bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
bool IsWindows = TargetTriple.isOSWindows();
bool IsFuchsia = TargetTriple.isOSFuchsia();
ShadowMapping Mapping;
if (LongSize == 32) {
// Android is always PIE, which means that the beginning of the address
// space is always available.
if (IsAndroid)
Mapping.Offset = 0;
else if (IsMIPS32)
Mapping.Offset = kMIPS32_ShadowOffset32;
else if (IsFreeBSD)
Mapping.Offset = kFreeBSD_ShadowOffset32;
else if (IsIOS)
// If we're targeting iOS and x86, the binary is built for iOS simulator.
Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32;
else if (IsWindows)
Mapping.Offset = kWindowsShadowOffset32;
else
Mapping.Offset = kDefaultShadowOffset32;
} else { // LongSize == 64
// Fuchsia is always PIE, which means that the beginning of the address
// space is always available.
if (IsFuchsia)
Mapping.Offset = 0;
else if (IsPPC64)
Mapping.Offset = kPPC64_ShadowOffset64;
else if (IsSystemZ)
Mapping.Offset = kSystemZ_ShadowOffset64;
else if (IsFreeBSD)
Mapping.Offset = kFreeBSD_ShadowOffset64;
else if (IsPS4CPU)
Mapping.Offset = kPS4CPU_ShadowOffset64;
else if (IsLinux && IsX86_64) {
if (IsKasan)
Mapping.Offset = kLinuxKasan_ShadowOffset64;
else
Mapping.Offset = kSmallX86_64ShadowOffset;
} else if (IsWindows && IsX86_64) {
Mapping.Offset = kWindowsShadowOffset64;
} else if (IsMIPS64)
Mapping.Offset = kMIPS64_ShadowOffset64;
else if (IsIOS)
// If we're targeting iOS and x86, the binary is built for iOS simulator.
// We are using dynamic shadow offset on the 64-bit devices.
Mapping.Offset =
IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
else if (IsAArch64)
Mapping.Offset = kAArch64_ShadowOffset64;
else
Mapping.Offset = kDefaultShadowOffset64;
}
if (ClForceDynamicShadow) {
Mapping.Offset = kDynamicShadowSentinel;
}
Mapping.Scale = kDefaultShadowScale;
if (ClMappingScale.getNumOccurrences() > 0) {
Mapping.Scale = ClMappingScale;
}
if (ClMappingOffset.getNumOccurrences() > 0) {
Mapping.Offset = ClMappingOffset;
}
// OR-ing shadow offset if more efficient (at least on x86) if the offset
// is a power of two, but on ppc64 we have to use add since the shadow
// offset is not necessary 1/8-th of the address space. On SystemZ,
// we could OR the constant in a single instruction, but it's more
// efficient to load it once and use indexed addressing.
Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
!(Mapping.Offset & (Mapping.Offset - 1)) &&
Mapping.Offset != kDynamicShadowSentinel;
return Mapping;
}
static size_t RedzoneSizeForScale(int MappingScale) {
// Redzone used for stack and globals is at least 32 bytes.
// For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
return std::max(32U, 1U << MappingScale);
}
/// AddressSanitizer: instrument the code in module to find memory bugs.
struct AddressSanitizer : public FunctionPass {
explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false,
bool UseAfterScope = false)
: FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
Recover(Recover || ClRecover),
UseAfterScope(UseAfterScope || ClUseAfterScope),
LocalDynamicShadow(nullptr) {
initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
}
StringRef getPassName() const override {
return "AddressSanitizerFunctionPass";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
uint64_t ArraySize = 1;
if (AI.isArrayAllocation()) {
const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
assert(CI && "non-constant array size");
ArraySize = CI->getZExtValue();
}
Type *Ty = AI.getAllocatedType();
uint64_t SizeInBytes =
AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
return SizeInBytes * ArraySize;
}
/// Check if we want (and can) handle this alloca.
bool isInterestingAlloca(const AllocaInst &AI);
/// If it is an interesting memory access, return the PointerOperand
/// and set IsWrite/Alignment. Otherwise return nullptr.
/// MaybeMask is an output parameter for the mask Value, if we're looking at a
/// masked load/store.
Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
uint64_t *TypeSize, unsigned *Alignment,
Value **MaybeMask = nullptr);
void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
bool UseCalls, const DataLayout &DL);
void instrumentPointerComparisonOrSubtraction(Instruction *I);
void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
Value *Addr, uint32_t TypeSize, bool IsWrite,
Value *SizeArgument, bool UseCalls, uint32_t Exp);
void instrumentUnusualSizeOrAlignment(Instruction *I,
Instruction *InsertBefore, Value *Addr,
uint32_t TypeSize, bool IsWrite,
Value *SizeArgument, bool UseCalls,
uint32_t Exp);
Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
Value *ShadowValue, uint32_t TypeSize);
Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
bool IsWrite, size_t AccessSizeIndex,
Value *SizeArgument, uint32_t Exp);
void instrumentMemIntrinsic(MemIntrinsic *MI);
Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
bool runOnFunction(Function &F) override;
bool maybeInsertAsanInitAtFunctionEntry(Function &F);
void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
void markEscapedLocalAllocas(Function &F);
bool doInitialization(Module &M) override;
bool doFinalization(Module &M) override;
static char ID; // Pass identification, replacement for typeid
DominatorTree &getDominatorTree() const { return *DT; }
private:
void initializeCallbacks(Module &M);
bool LooksLikeCodeInBug11395(Instruction *I);
bool GlobalIsLinkerInitialized(GlobalVariable *G);
bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
uint64_t TypeSize) const;
/// Helper to cleanup per-function state.
struct FunctionStateRAII {
AddressSanitizer *Pass;
FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
assert(Pass->ProcessedAllocas.empty() &&
"last pass forgot to clear cache");
assert(!Pass->LocalDynamicShadow);
}
~FunctionStateRAII() {
Pass->LocalDynamicShadow = nullptr;
Pass->ProcessedAllocas.clear();
}
};
LLVMContext *C;
Triple TargetTriple;
int LongSize;
bool CompileKernel;
bool Recover;
bool UseAfterScope;
Type *IntptrTy;
ShadowMapping Mapping;
DominatorTree *DT;
Function *AsanHandleNoReturnFunc;
Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
// This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
// This array is indexed by AccessIsWrite and Experiment.
Function *AsanErrorCallbackSized[2][2];
Function *AsanMemoryAccessCallbackSized[2][2];
Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
InlineAsm *EmptyAsm;
Value *LocalDynamicShadow;
GlobalsMetadata GlobalsMD;
DenseMap<const AllocaInst *, bool> ProcessedAllocas;
friend struct FunctionStackPoisoner;
};
class AddressSanitizerModule : public ModulePass {
public:
explicit AddressSanitizerModule(bool CompileKernel = false,
bool Recover = false)
: ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
Recover(Recover || ClRecover) {}
bool runOnModule(Module &M) override;
static char ID; // Pass identification, replacement for typeid
StringRef getPassName() const override { return "AddressSanitizerModule"; }
private:
void initializeCallbacks(Module &M);
bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers);
void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers);
void
InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers);
GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
StringRef OriginalName);
void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata);
IRBuilder<> CreateAsanModuleDtor(Module &M);
bool ShouldInstrumentGlobal(GlobalVariable *G);
bool ShouldUseMachOGlobalsSection() const;
StringRef getGlobalMetadataSection() const;
void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
size_t MinRedzoneSizeForGlobal() const {
return RedzoneSizeForScale(Mapping.Scale);
}
GlobalsMetadata GlobalsMD;
bool CompileKernel;
bool Recover;
Type *IntptrTy;
LLVMContext *C;
Triple TargetTriple;
ShadowMapping Mapping;
Function *AsanPoisonGlobals;
Function *AsanUnpoisonGlobals;
Function *AsanRegisterGlobals;
Function *AsanUnregisterGlobals;
Function *AsanRegisterImageGlobals;
Function *AsanUnregisterImageGlobals;
};
// Stack poisoning does not play well with exception handling.
// When an exception is thrown, we essentially bypass the code
// that unpoisones the stack. This is why the run-time library has
// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
// stack in the interceptor. This however does not work inside the
// actual function which catches the exception. Most likely because the
// compiler hoists the load of the shadow value somewhere too high.
// This causes asan to report a non-existing bug on 453.povray.
// It sounds like an LLVM bug.
struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
Function &F;
AddressSanitizer &ASan;
DIBuilder DIB;
LLVMContext *C;
Type *IntptrTy;
Type *IntptrPtrTy;
ShadowMapping Mapping;
SmallVector<AllocaInst *, 16> AllocaVec;
SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
SmallVector<Instruction *, 8> RetVec;
unsigned StackAlignment;
Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
*AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
Function *AsanSetShadowFunc[0x100] = {};
Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
// Stores a place and arguments of poisoning/unpoisoning call for alloca.
struct AllocaPoisonCall {
IntrinsicInst *InsBefore;
AllocaInst *AI;
uint64_t Size;
bool DoPoison;
};
SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
SmallVector<AllocaInst *, 1> DynamicAllocaVec;
SmallVector<IntrinsicInst *, 1> StackRestoreVec;
AllocaInst *DynamicAllocaLayout = nullptr;
IntrinsicInst *LocalEscapeCall = nullptr;
// Maps Value to an AllocaInst from which the Value is originated.
typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
AllocaForValueMapTy AllocaForValue;
bool HasNonEmptyInlineAsm = false;
bool HasReturnsTwiceCall = false;
std::unique_ptr<CallInst> EmptyInlineAsm;
FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
: F(F),
ASan(ASan),
DIB(*F.getParent(), /*AllowUnresolved*/ false),
C(ASan.C),
IntptrTy(ASan.IntptrTy),
IntptrPtrTy(PointerType::get(IntptrTy, 0)),
Mapping(ASan.Mapping),
StackAlignment(1 << Mapping.Scale),
EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
bool runOnFunction() {
if (!ClStack) return false;
// Collect alloca, ret, lifetime instructions etc.
for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
initializeCallbacks(*F.getParent());
processDynamicAllocas();
processStaticAllocas();
if (ClDebugStack) {
DEBUG(dbgs() << F);
}
return true;
}
// Finds all Alloca instructions and puts
// poisoned red zones around all of them.
// Then unpoison everything back before the function returns.
void processStaticAllocas();
void processDynamicAllocas();
void createDynamicAllocasInitStorage();
// ----------------------- Visitors.
/// \brief Collect all Ret instructions.
void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
/// \brief Collect all Resume instructions.
void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
/// \brief Collect all CatchReturnInst instructions.
void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
Value *SavedStack) {
IRBuilder<> IRB(InstBefore);
Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
// When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
// need to adjust extracted SP to compute the address of the most recent
// alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
// this purpose.
if (!isa<ReturnInst>(InstBefore)) {
Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
{IntptrTy});
Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
DynamicAreaOffset);
}
IRB.CreateCall(AsanAllocasUnpoisonFunc,
{IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
}
// Unpoison dynamic allocas redzones.
void unpoisonDynamicAllocas() {
for (auto &Ret : RetVec)
unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
for (auto &StackRestoreInst : StackRestoreVec)
unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
StackRestoreInst->getOperand(0));
}
// Deploy and poison redzones around dynamic alloca call. To do this, we
// should replace this call with another one with changed parameters and
// replace all its uses with new address, so
// addr = alloca type, old_size, align
// is replaced by
// new_size = (old_size + additional_size) * sizeof(type)
// tmp = alloca i8, new_size, max(align, 32)
// addr = tmp + 32 (first 32 bytes are for the left redzone).
// Additional_size is added to make new memory allocation contain not only
// requested memory, but also left, partial and right redzones.
void handleDynamicAllocaCall(AllocaInst *AI);
/// \brief Collect Alloca instructions we want (and can) handle.
void visitAllocaInst(AllocaInst &AI) {
if (!ASan.isInterestingAlloca(AI)) {
if (AI.isStaticAlloca()) {
// Skip over allocas that are present *before* the first instrumented
// alloca, we don't want to move those around.
if (AllocaVec.empty())
return;
StaticAllocasToMoveUp.push_back(&AI);
}
return;
}
StackAlignment = std::max(StackAlignment, AI.getAlignment());
if (!AI.isStaticAlloca())
DynamicAllocaVec.push_back(&AI);
else
AllocaVec.push_back(&AI);
}
/// \brief Collect lifetime intrinsic calls to check for use-after-scope
/// errors.
void visitIntrinsicInst(IntrinsicInst &II) {
Intrinsic::ID ID = II.getIntrinsicID();
if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
if (!ASan.UseAfterScope)
return;
if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
return;
// Found lifetime intrinsic, add ASan instrumentation if necessary.
ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
// If size argument is undefined, don't do anything.
if (Size->isMinusOne()) return;
// Check that size doesn't saturate uint64_t and can
// be stored in IntptrTy.
const uint64_t SizeValue = Size->getValue().getLimitedValue();
if (SizeValue == ~0ULL ||
!ConstantInt::isValueValidForType(IntptrTy, SizeValue))
return;
// Find alloca instruction that corresponds to llvm.lifetime argument.
AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
if (!AI || !ASan.isInterestingAlloca(*AI))
return;
bool DoPoison = (ID == Intrinsic::lifetime_end);
AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
if (AI->isStaticAlloca())
StaticAllocaPoisonCallVec.push_back(APC);
else if (ClInstrumentDynamicAllocas)
DynamicAllocaPoisonCallVec.push_back(APC);
}
void visitCallSite(CallSite CS) {
Instruction *I = CS.getInstruction();
if (CallInst *CI = dyn_cast<CallInst>(I)) {
HasNonEmptyInlineAsm |=
CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
HasReturnsTwiceCall |= CI->canReturnTwice();
}
}
// ---------------------- Helpers.
void initializeCallbacks(Module &M);
bool doesDominateAllExits(const Instruction *I) const {
for (auto Ret : RetVec) {
if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
}
return true;
}
/// Finds alloca where the value comes from.
AllocaInst *findAllocaForValue(Value *V);
// Copies bytes from ShadowBytes into shadow memory for indexes where
// ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
// ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
IRBuilder<> &IRB, Value *ShadowBase);
void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
size_t Begin, size_t End, IRBuilder<> &IRB,
Value *ShadowBase);
void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
ArrayRef<uint8_t> ShadowBytes, size_t Begin,
size_t End, IRBuilder<> &IRB, Value *ShadowBase);
void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
bool Dynamic);
PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
Instruction *ThenTerm, Value *ValueIfFalse);
};
} // anonymous namespace
char AddressSanitizer::ID = 0;
INITIALIZE_PASS_BEGIN(
AddressSanitizer, "asan",
"AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(
AddressSanitizer, "asan",
"AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
false)
FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
bool Recover,
bool UseAfterScope) {
assert(!CompileKernel || Recover);
return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
}
char AddressSanitizerModule::ID = 0;
INITIALIZE_PASS(
AddressSanitizerModule, "asan-module",
"AddressSanitizer: detects use-after-free and out-of-bounds bugs."
"ModulePass",
false, false)
ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
bool Recover) {
assert(!CompileKernel || Recover);
return new AddressSanitizerModule(CompileKernel, Recover);
}
static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
size_t Res = countTrailingZeros(TypeSize / 8);
assert(Res < kNumberOfAccessSizes);
return Res;
}
// \brief Create a constant for Str so that we can pass it to the run-time lib.
static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
bool AllowMerging) {
Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
// We use private linkage for module-local strings. If they can be merged
// with another one, we set the unnamed_addr attribute.
GlobalVariable *GV =
new GlobalVariable(M, StrConst->getType(), true,
GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
return GV;
}
/// \brief Create a global describing a source location.
static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
LocationMetadata MD) {
Constant *LocData[] = {
createPrivateGlobalForString(M, MD.Filename, true),
ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
};
auto LocStruct = ConstantStruct::getAnon(LocData);
auto GV = new GlobalVariable(M, LocStruct->getType(), true,
GlobalValue::PrivateLinkage, LocStruct,
kAsanGenPrefix);
GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
return GV;
}
/// \brief Check if \p G has been created by a trusted compiler pass.
static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
// Do not instrument asan globals.
if (G->getName().startswith(kAsanGenPrefix) ||
G->getName().startswith(kSanCovGenPrefix) ||
G->getName().startswith(kODRGenPrefix))
return true;
// Do not instrument gcov counter arrays.
if (G->getName() == "__llvm_gcov_ctr")
return true;
return false;
}
Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
// Shadow >> scale
Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
if (Mapping.Offset == 0) return Shadow;
// (Shadow >> scale) | offset
Value *ShadowBase;
if (LocalDynamicShadow)
ShadowBase = LocalDynamicShadow;
else
ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
if (Mapping.OrShadowOffset)
return IRB.CreateOr(Shadow, ShadowBase);
else
return IRB.CreateAdd(Shadow, ShadowBase);
}
// Instrument memset/memmove/memcpy
void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
IRBuilder<> IRB(MI);
if (isa<MemTransferInst>(MI)) {
IRB.CreateCall(
isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
{IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
} else if (isa<MemSetInst>(MI)) {
IRB.CreateCall(
AsanMemset,
{IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
}
MI->eraseFromParent();
}
/// Check if we want (and can) handle this alloca.
bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
return PreviouslySeenAllocaInfo->getSecond();
bool IsInteresting =
(AI.getAllocatedType()->isSized() &&
// alloca() may be called with 0 size, ignore it.
((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
// We are only interested in allocas not promotable to registers.
// Promotable allocas are common under -O0.
(!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
// inalloca allocas are not treated as static, and we don't want
// dynamic alloca instrumentation for them as well.
!AI.isUsedWithInAlloca() &&
// swifterror allocas are register promoted by ISel
!AI.isSwiftError());
ProcessedAllocas[&AI] = IsInteresting;
return IsInteresting;
}
Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
bool *IsWrite,
uint64_t *TypeSize,
unsigned *Alignment,
Value **MaybeMask) {
// Skip memory accesses inserted by another instrumentation.
if (I->getMetadata("nosanitize")) return nullptr;
// Do not instrument the load fetching the dynamic shadow address.
if (LocalDynamicShadow == I)
return nullptr;
Value *PtrOperand = nullptr;
const DataLayout &DL = I->getModule()->getDataLayout();
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
if (!ClInstrumentReads) return nullptr;
*IsWrite = false;
*TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
*Alignment = LI->getAlignment();
PtrOperand = LI->getPointerOperand();
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
if (!ClInstrumentWrites) return nullptr;
*IsWrite = true;
*TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
*Alignment = SI->getAlignment();
PtrOperand = SI->getPointerOperand();
} else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
if (!ClInstrumentAtomics) return nullptr;
*IsWrite = true;
*TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
*Alignment = 0;
PtrOperand = RMW->getPointerOperand();
} else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
if (!ClInstrumentAtomics) return nullptr;
*IsWrite = true;
*TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
*Alignment = 0;
PtrOperand = XCHG->getPointerOperand();
} else if (auto CI = dyn_cast<CallInst>(I)) {
auto *F = dyn_cast<Function>(CI->getCalledValue());
if (F && (F->getName().startswith("llvm.masked.load.") ||
F->getName().startswith("llvm.masked.store."))) {
unsigned OpOffset = 0;
if (F->getName().startswith("llvm.masked.store.")) {
if (!ClInstrumentWrites)
return nullptr;
// Masked store has an initial operand for the value.
OpOffset = 1;
*IsWrite = true;
} else {
if (!ClInstrumentReads)
return nullptr;
*IsWrite = false;
}
auto BasePtr = CI->getOperand(0 + OpOffset);
auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
*TypeSize = DL.getTypeStoreSizeInBits(Ty);
if (auto AlignmentConstant =
dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
*Alignment = (unsigned)AlignmentConstant->getZExtValue();
else
*Alignment = 1; // No alignment guarantees. We probably got Undef
if (MaybeMask)
*MaybeMask = CI->getOperand(2 + OpOffset);
PtrOperand = BasePtr;
}
}
if (PtrOperand) {
// Do not instrument acesses from different address spaces; we cannot deal
// with them.
Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
if (PtrTy->getPointerAddressSpace() != 0)
return nullptr;
// Ignore swifterror addresses.
// swifterror memory addresses are mem2reg promoted by instruction
// selection. As such they cannot have regular uses like an instrumentation
// function and it makes no sense to track them as memory.
if (PtrOperand->isSwiftError())
return nullptr;
}
// Treat memory accesses to promotable allocas as non-interesting since they
// will not cause memory violations. This greatly speeds up the instrumented
// executable at -O0.
if (ClSkipPromotableAllocas)
if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
return isInterestingAlloca(*AI) ? AI : nullptr;
return PtrOperand;
}
static bool isPointerOperand(Value *V) {
return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
}
// This is a rough heuristic; it may cause both false positives and
// false negatives. The proper implementation requires cooperation with
// the frontend.
static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
if (!Cmp->isRelational()) return false;
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
if (BO->getOpcode() != Instruction::Sub) return false;
} else {
return false;
}
return isPointerOperand(I->getOperand(0)) &&
isPointerOperand(I->getOperand(1));
}
bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
// If a global variable does not have dynamic initialization we don't
// have to instrument it. However, if a global does not have initializer
// at all, we assume it has dynamic initializer (in other TU).
return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
}
void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
Instruction *I) {
IRBuilder<> IRB(I);
Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
for (Value *&i : Param) {
if (i->getType()->isPointerTy())
i = IRB.CreatePointerCast(i, IntptrTy);
}
IRB.CreateCall(F, Param);
}
static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
Instruction *InsertBefore, Value *Addr,
unsigned Alignment, unsigned Granularity,
uint32_t TypeSize, bool IsWrite,
Value *SizeArgument, bool UseCalls,
uint32_t Exp) {
// Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
// if the data is properly aligned.
if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
TypeSize == 128) &&
(Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
nullptr, UseCalls, Exp);
Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
IsWrite, nullptr, UseCalls, Exp);
}
static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
const DataLayout &DL, Type *IntptrTy,
Value *Mask, Instruction *I,
Value *Addr, unsigned Alignment,
unsigned Granularity, uint32_t TypeSize,
bool IsWrite, Value *SizeArgument,
bool UseCalls, uint32_t Exp) {
auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
unsigned Num = VTy->getVectorNumElements();
auto Zero = ConstantInt::get(IntptrTy, 0);
for (unsigned Idx = 0; Idx < Num; ++Idx) {
Value *InstrumentedAddress = nullptr;
Instruction *InsertBefore = I;
if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
// dyn_cast as we might get UndefValue
if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
if (Masked->isNullValue())
// Mask is constant false, so no instrumentation needed.
continue;
// If we have a true or undef value, fall through to doInstrumentAddress
// with InsertBefore == I
}
} else {
IRBuilder<> IRB(I);
Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
InsertBefore = ThenTerm;
}
IRBuilder<> IRB(InsertBefore);
InstrumentedAddress =
IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
Granularity, ElemTypeSize, IsWrite, SizeArgument,
UseCalls, Exp);
}
}
void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
Instruction *I, bool UseCalls,
const DataLayout &DL) {
bool IsWrite = false;
unsigned Alignment = 0;
uint64_t TypeSize = 0;
Value *MaybeMask = nullptr;
Value *Addr =
isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
assert(Addr);
// Optimization experiments.
// The experiments can be used to evaluate potential optimizations that remove
// instrumentation (assess false negatives). Instead of completely removing
// some instrumentation, you set Exp to a non-zero value (mask of optimization
// experiments that want to remove instrumentation of this instruction).
// If Exp is non-zero, this pass will emit special calls into runtime
// (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
// make runtime terminate the program in a special way (with a different
// exit status). Then you run the new compiler on a buggy corpus, collect
// the special terminations (ideally, you don't see them at all -- no false
// negatives) and make the decision on the optimization.
uint32_t Exp = ClForceExperiment;
if (ClOpt && ClOptGlobals) {
// If initialization order checking is disabled, a simple access to a
// dynamically initialized global is always valid.
GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
NumOptimizedAccessesToGlobalVar++;
return;
}
}
if (ClOpt && ClOptStack) {
// A direct inbounds access to a stack variable is always valid.
if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
NumOptimizedAccessesToStackVar++;
return;
}
}
if (IsWrite)
NumInstrumentedWrites++;
else
NumInstrumentedReads++;
unsigned Granularity = 1 << Mapping.Scale;
if (MaybeMask) {
instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
Alignment, Granularity, TypeSize, IsWrite,
nullptr, UseCalls, Exp);
} else {
doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
IsWrite, nullptr, UseCalls, Exp);
}
}
Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
Value *Addr, bool IsWrite,
size_t AccessSizeIndex,
Value *SizeArgument,
uint32_t Exp) {
IRBuilder<> IRB(InsertBefore);
Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
CallInst *Call = nullptr;
if (SizeArgument) {
if (Exp == 0)
Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
{Addr, SizeArgument});
else
Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
{Addr, SizeArgument, ExpVal});
} else {
if (Exp == 0)
Call =
IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
else
Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
{Addr, ExpVal});
}
// We don't do Call->setDoesNotReturn() because the BB already has
// UnreachableInst at the end.
// This EmptyAsm is required to avoid callback merge.
IRB.CreateCall(EmptyAsm, {});
return Call;
}
Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
Value *ShadowValue,
uint32_t TypeSize) {
size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
// Addr & (Granularity - 1)
Value *LastAccessedByte =
IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
// (Addr & (Granularity - 1)) + size - 1
if (TypeSize / 8 > 1)
LastAccessedByte = IRB.CreateAdd(
LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
// (uint8_t) ((Addr & (Granularity-1)) + size - 1)
LastAccessedByte =
IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
// ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
}
void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
Instruction *InsertBefore, Value *Addr,
uint32_t TypeSize, bool IsWrite,
Value *SizeArgument, bool UseCalls,
uint32_t Exp) {
IRBuilder<> IRB(InsertBefore);
Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
if (UseCalls) {
if (Exp == 0)
IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
AddrLong);
else
IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
{AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
return;
}
Type *ShadowTy =
IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
Value *ShadowPtr = memToShadow(AddrLong, IRB);
Value *CmpVal = Constant::getNullValue(ShadowTy);
Value *ShadowValue =
IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
size_t Granularity = 1ULL << Mapping.Scale;
TerminatorInst *CrashTerm = nullptr;
if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
// We use branch weights for the slow path check, to indicate that the slow
// path is rarely taken. This seems to be the case for SPEC benchmarks.
TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
assert(cast<BranchInst>(CheckTerm)->isUnconditional());
BasicBlock *NextBB = CheckTerm->getSuccessor(0);
IRB.SetInsertPoint(CheckTerm);
Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
if (Recover) {
CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
} else {
BasicBlock *CrashBlock =
BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
CrashTerm = new UnreachableInst(*C, CrashBlock);
BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
ReplaceInstWithInst(CheckTerm, NewTerm);
}
} else {
CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
}
Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
AccessSizeIndex, SizeArgument, Exp);
Crash->setDebugLoc(OrigIns->getDebugLoc());
}
// Instrument unusual size or unusual alignment.
// We can not do it with a single check, so we do 1-byte check for the first
// and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
// to report the actual access size.
void AddressSanitizer::instrumentUnusualSizeOrAlignment(
Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
IRBuilder<> IRB(InsertBefore);
Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
if (UseCalls) {
if (Exp == 0)
IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
{AddrLong, Size});
else
IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
{AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
} else {
Value *LastByte = IRB.CreateIntToPtr(
IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
Addr->getType());
instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
}
}
void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
GlobalValue *ModuleName) {
// Set up the arguments to our poison/unpoison functions.
IRBuilder<> IRB(&GlobalInit.front(),
GlobalInit.front().getFirstInsertionPt());
// Add a call to poison all external globals before the given function starts.
Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
// Add calls to unpoison all globals before each return instruction.
for (auto &BB : GlobalInit.getBasicBlockList())
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
CallInst::Create(AsanUnpoisonGlobals, "", RI);
}
void AddressSanitizerModule::createInitializerPoisonCalls(
Module &M, GlobalValue *ModuleName) {
GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
for (Use &OP : CA->operands()) {
if (isa<ConstantAggregateZero>(OP)) continue;
ConstantStruct *CS = cast<ConstantStruct>(OP);
// Must have a function or null ptr.
if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
if (F->getName() == kAsanModuleCtorName) continue;
ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
// Don't instrument CTORs that will run before asan.module_ctor.
if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
poisonOneInitializer(*F, ModuleName);
}
}
}
bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
Type *Ty = G->getValueType();
DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
if (GlobalsMD.get(G).IsBlacklisted) return false;
if (!Ty->isSized()) return false;
if (!G->hasInitializer()) return false;
if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
// Touch only those globals that will not be defined in other modules.
// Don't handle ODR linkage types and COMDATs since other modules may be built
// without ASan.
if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
G->getLinkage() != GlobalVariable::PrivateLinkage &&
G->getLinkage() != GlobalVariable::InternalLinkage)
return false;
if (G->hasComdat()) return false;
// Two problems with thread-locals:
// - The address of the main thread's copy can't be computed at link-time.
// - Need to poison all copies, not just the main thread's one.
if (G->isThreadLocal()) return false;
// For now, just ignore this Global if the alignment is large.
if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
if (G->hasSection()) {
StringRef Section = G->getSection();
// Globals from llvm.metadata aren't emitted, do not instrument them.
if (Section == "llvm.metadata") return false;
// Do not instrument globals from special LLVM sections.
if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
// Do not instrument function pointers to initialization and termination
// routines: dynamic linker will not properly handle redzones.
if (Section.startswith(".preinit_array") ||
Section.startswith(".init_array") ||
Section.startswith(".fini_array")) {
return false;
}
// Callbacks put into the CRT initializer/terminator sections
// should not be instrumented.
// See https://code.google.com/p/address-sanitizer/issues/detail?id=305
// and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
if (Section.startswith(".CRT")) {
DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
return false;
}
if (TargetTriple.isOSBinFormatMachO()) {
StringRef ParsedSegment, ParsedSection;
unsigned TAA = 0, StubSize = 0;
bool TAAParsed;
std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
assert(ErrorCode.empty() && "Invalid section specifier.");
// Ignore the globals from the __OBJC section. The ObjC runtime assumes
// those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
// them.
if (ParsedSegment == "__OBJC" ||
(ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
return false;
}
// See http://code.google.com/p/address-sanitizer/issues/detail?id=32
// Constant CFString instances are compiled in the following way:
// -- the string buffer is emitted into
// __TEXT,__cstring,cstring_literals
// -- the constant NSConstantString structure referencing that buffer
// is placed into __DATA,__cfstring
// Therefore there's no point in placing redzones into __DATA,__cfstring.
// Moreover, it causes the linker to crash on OS X 10.7
if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
return false;
}
// The linker merges the contents of cstring_literals and removes the
// trailing zeroes.
if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
return false;
}
}
}
return true;
}
// On Mach-O platforms, we emit global metadata in a separate section of the
// binary in order to allow the linker to properly dead strip. This is only
// supported on recent versions of ld64.
bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
if (!ClUseMachOGlobalsSection)
return false;
if (!TargetTriple.isOSBinFormatMachO())
return false;
if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
return true;
if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
return true;
if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
return true;
return false;
}
StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
switch (TargetTriple.getObjectFormat()) {
case Triple::COFF: return ".ASAN$GL";
case Triple::ELF: return "asan_globals";
case Triple::MachO: return "__DATA,__asan_globals,regular";
default: break;
}
llvm_unreachable("unsupported object format");
}
void AddressSanitizerModule::initializeCallbacks(Module &M) {
IRBuilder<> IRB(*C);
// Declare our poisoning and unpoisoning functions.
AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
// Declare functions that register/unregister globals.
AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
IntptrTy, IntptrTy, nullptr));
AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
// Declare the functions that find globals in a shared object and then invoke
// the (un)register function on them.
AsanRegisterImageGlobals =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
AsanUnregisterImageGlobals =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
}
// Put the metadata and the instrumented global in the same group. This ensures
// that the metadata is discarded if the instrumented global is discarded.
void AddressSanitizerModule::SetComdatForGlobalMetadata(
GlobalVariable *G, GlobalVariable *Metadata) {
Module &M = *G->getParent();
Comdat *C = G->getComdat();
if (!C) {
if (!G->hasName()) {
// If G is unnamed, it must be internal. Give it an artificial name
// so we can put it in a comdat.
assert(G->hasLocalLinkage());
G->setName(Twine(kAsanGenPrefix) + "_anon_global");
}
C = M.getOrInsertComdat(G->getName());
// Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
if (TargetTriple.isOSBinFormatCOFF())
C->setSelectionKind(Comdat::NoDuplicates);
G->setComdat(C);
}
assert(G->hasComdat());
Metadata->setComdat(G->getComdat());
}
// Create a separate metadata global and put it in the appropriate ASan
// global registration section.
GlobalVariable *
AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer,
StringRef OriginalName) {
GlobalVariable *Metadata =
new GlobalVariable(M, Initializer->getType(), false,
GlobalVariable::InternalLinkage, Initializer,
Twine("__asan_global_") +
GlobalValue::getRealLinkageName(OriginalName));
Metadata->setSection(getGlobalMetadataSection());
return Metadata;
}
IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) {
Function *AsanDtorFunction =
Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
}
void AddressSanitizerModule::InstrumentGlobalsCOFF(
IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers) {
assert(ExtendedGlobals.size() == MetadataInitializers.size());
auto &DL = M.getDataLayout();
for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
Constant *Initializer = MetadataInitializers[i];
GlobalVariable *G = ExtendedGlobals[i];
GlobalVariable *Metadata =
CreateMetadataGlobal(M, Initializer, G->getName());
// The MSVC linker always inserts padding when linking incrementally. We
// cope with that by aligning each struct to its size, which must be a power
// of two.
unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
assert(isPowerOf2_32(SizeOfGlobalStruct) &&
"global metadata will not be padded appropriately");
Metadata->setAlignment(SizeOfGlobalStruct);
SetComdatForGlobalMetadata(G, Metadata);
}
}
void AddressSanitizerModule::InstrumentGlobalsMachO(
IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers) {
assert(ExtendedGlobals.size() == MetadataInitializers.size());
// On recent Mach-O platforms, use a structure which binds the liveness of
// the global variable to the metadata struct. Keep the list of "Liveness" GV
// created to be added to llvm.compiler.used
StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr);
SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
Constant *Initializer = MetadataInitializers[i];
GlobalVariable *G = ExtendedGlobals[i];
GlobalVariable *Metadata =
CreateMetadataGlobal(M, Initializer, G->getName());
// On recent Mach-O platforms, we emit the global metadata in a way that
// allows the linker to properly strip dead globals.
auto LivenessBinder = ConstantStruct::get(
LivenessTy, Initializer->getAggregateElement(0u),
ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr);
GlobalVariable *Liveness = new GlobalVariable(
M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
Twine("__asan_binder_") + G->getName());
Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
LivenessGlobals[i] = Liveness;
}
// Update llvm.compiler.used, adding the new liveness globals. This is
// needed so that during LTO these variables stay alive. The alternative
// would be to have the linker handling the LTO symbols, but libLTO
// current API does not expose access to the section for each symbol.
if (!LivenessGlobals.empty())
appendToCompilerUsed(M, LivenessGlobals);
// RegisteredFlag serves two purposes. First, we can pass it to dladdr()
// to look up the loaded image that contains it. Second, we can store in it
// whether registration has already occurred, to prevent duplicate
// registration.
//
// common linkage ensures that there is only one global per shared library.
GlobalVariable *RegisteredFlag = new GlobalVariable(
M, IntptrTy, false, GlobalVariable::CommonLinkage,
ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
IRB.CreateCall(AsanRegisterImageGlobals,
{IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
// We also need to unregister globals at the end, e.g., when a shared library
// gets closed.
IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
{IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
}
void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray(
IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers) {
assert(ExtendedGlobals.size() == MetadataInitializers.size());
unsigned N = ExtendedGlobals.size();
assert(N > 0);
// On platforms that don't have a custom metadata section, we emit an array
// of global metadata structures.
ArrayType *ArrayOfGlobalStructTy =
ArrayType::get(MetadataInitializers[0]->getType(), N);
auto AllGlobals = new GlobalVariable(
M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
IRB.CreateCall(AsanRegisterGlobals,
{IRB.CreatePointerCast(AllGlobals, IntptrTy),
ConstantInt::get(IntptrTy, N)});
// We also need to unregister globals at the end, e.g., when a shared library
// gets closed.
IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
IRB_Dtor.CreateCall(AsanUnregisterGlobals,
{IRB.CreatePointerCast(AllGlobals, IntptrTy),
ConstantInt::get(IntptrTy, N)});
}
// This function replaces all global variables with new variables that have
// trailing redzones. It also creates a function that poisons
// redzones and inserts this function into llvm.global_ctors.
bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
GlobalsMD.init(M);
SmallVector<GlobalVariable *, 16> GlobalsToChange;
for (auto &G : M.globals()) {
if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
}
size_t n = GlobalsToChange.size();
if (n == 0) return false;
auto &DL = M.getDataLayout();
// A global is described by a structure
// size_t beg;
// size_t size;
// size_t size_with_redzone;
// const char *name;
// const char *module_name;
// size_t has_dynamic_init;
// void *source_location;
// size_t odr_indicator;
// We initialize an array of such structures and pass it to a run-time call.
StructType *GlobalStructTy =
StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
IntptrTy, IntptrTy, IntptrTy, nullptr);
SmallVector<GlobalVariable *, 16> NewGlobals(n);
SmallVector<Constant *, 16> Initializers(n);
bool HasDynamicallyInitializedGlobals = false;
// We shouldn't merge same module names, as this string serves as unique
// module ID in runtime.
GlobalVariable *ModuleName = createPrivateGlobalForString(
M, M.getModuleIdentifier(), /*AllowMerging*/ false);
for (size_t i = 0; i < n; i++) {
static const uint64_t kMaxGlobalRedzone = 1 << 18;
GlobalVariable *G = GlobalsToChange[i];
auto MD = GlobalsMD.get(G);
StringRef NameForGlobal = G->getName();
// Create string holding the global name (use global name from metadata
// if it's available, otherwise just write the name of global variable).
GlobalVariable *Name = createPrivateGlobalForString(
M, MD.Name.empty() ? NameForGlobal : MD.Name,
/*AllowMerging*/ true);
Type *Ty = G->getValueType();
uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
uint64_t MinRZ = MinRedzoneSizeForGlobal();
// MinRZ <= RZ <= kMaxGlobalRedzone
// and trying to make RZ to be ~ 1/4 of SizeInBytes.
uint64_t RZ = std::max(
MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
uint64_t RightRedzoneSize = RZ;
// Round up to MinRZ
if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
Constant *NewInitializer =
ConstantStruct::get(NewTy, G->getInitializer(),
Constant::getNullValue(RightRedZoneTy), nullptr);
// Create a new global variable with enough space for a redzone.
GlobalValue::LinkageTypes Linkage = G->getLinkage();
if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
Linkage = GlobalValue::InternalLinkage;
GlobalVariable *NewGlobal =
new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
"", G, G->getThreadLocalMode());
NewGlobal->copyAttributesFrom(G);
NewGlobal->setAlignment(MinRZ);
// Move null-terminated C strings to "__asan_cstring" section on Darwin.
if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
G->isConstant()) {
auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
if (Seq && Seq->isCString())
NewGlobal->setSection("__TEXT,__asan_cstring,regular");
}
// Transfer the debug info. The payload starts at offset zero so we can
// copy the debug info over as is.
SmallVector<DIGlobalVariableExpression *, 1> GVs;
G->getDebugInfo(GVs);
for (auto *GV : GVs)
NewGlobal->addDebugInfo(GV);
Value *Indices2[2];
Indices2[0] = IRB.getInt32(0);
Indices2[1] = IRB.getInt32(0);
G->replaceAllUsesWith(
ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
NewGlobal->takeName(G);
G->eraseFromParent();
NewGlobals[i] = NewGlobal;
Constant *SourceLoc;
if (!MD.SourceLoc.empty()) {
auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
} else {
SourceLoc = ConstantInt::get(IntptrTy, 0);
}
Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
GlobalValue *InstrumentedGlobal = NewGlobal;
bool CanUsePrivateAliases =
TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO() ||
TargetTriple.isOSBinFormatWasm();
if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
// Create local alias for NewGlobal to avoid crash on ODR between
// instrumented and non-instrumented libraries.
auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
NameForGlobal + M.getName(), NewGlobal);
// With local aliases, we need to provide another externally visible
// symbol __odr_asan_XXX to detect ODR violation.
auto *ODRIndicatorSym =
new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
Constant::getNullValue(IRB.getInt8Ty()),
kODRGenPrefix + NameForGlobal, nullptr,
NewGlobal->getThreadLocalMode());
// Set meaningful attributes for indicator symbol.
ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
ODRIndicatorSym->setAlignment(1);
ODRIndicator = ODRIndicatorSym;
InstrumentedGlobal = GA;
}
Constant *Initializer = ConstantStruct::get(
GlobalStructTy,
ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
ConstantInt::get(IntptrTy, SizeInBytes),
ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
ConstantExpr::getPointerCast(Name, IntptrTy),
ConstantExpr::getPointerCast(ModuleName, IntptrTy),
ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr);
if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
Initializers[i] = Initializer;
}
if (TargetTriple.isOSBinFormatCOFF()) {
InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
} else if (ShouldUseMachOGlobalsSection()) {
InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
} else {
InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
}
// Create calls for poisoning before initializers run and unpoisoning after.
if (HasDynamicallyInitializedGlobals)
createInitializerPoisonCalls(M, ModuleName);
DEBUG(dbgs() << M);
return true;
}
bool AddressSanitizerModule::runOnModule(Module &M) {
C = &(M.getContext());
int LongSize = M.getDataLayout().getPointerSizeInBits();
IntptrTy = Type::getIntNTy(*C, LongSize);
TargetTriple = Triple(M.getTargetTriple());
Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
initializeCallbacks(M);
if (CompileKernel)
return false;
Function *AsanCtorFunction;
std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{},
/*InitArgs=*/{}, kAsanVersionCheckName);
appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
bool Changed = false;
// TODO(glider): temporarily disabled globals instrumentation for KASan.
if (ClGlobals) {
IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
Changed |= InstrumentGlobals(IRB, M);
}
return Changed;
}
void AddressSanitizer::initializeCallbacks(Module &M) {
IRBuilder<> IRB(*C);
// Create __asan_report* callbacks.
// IsWrite, TypeSize and Exp are encoded in the function name.
for (int Exp = 0; Exp < 2; Exp++) {
for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
const std::string TypeStr = AccessIsWrite ? "store" : "load";
const std::string ExpStr = Exp ? "exp_" : "";
const std::string SuffixStr = CompileKernel ? "N" : "_n";
const std::string EndingStr = Recover ? "_noabort" : "";
Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
AsanErrorCallbackSized[AccessIsWrite][Exp] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr,
IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
AccessSizeIndex++) {
const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
}
}
}
const std::string MemIntrinCallbackPrefix =
CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
// We insert an empty inline asm after __asan_report* to avoid callback merge.
EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
StringRef(""), StringRef(""),
/*hasSideEffects=*/true);
}
// virtual
bool AddressSanitizer::doInitialization(Module &M) {
// Initialize the private fields. No one has accessed them before.
GlobalsMD.init(M);
C = &(M.getContext());
LongSize = M.getDataLayout().getPointerSizeInBits();
IntptrTy = Type::getIntNTy(*C, LongSize);
TargetTriple = Triple(M.getTargetTriple());
Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
return true;
}
bool AddressSanitizer::doFinalization(Module &M) {
GlobalsMD.reset();
return false;
}
bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
// For each NSObject descendant having a +load method, this method is invoked
// by the ObjC runtime before any of the static constructors is called.
// Therefore we need to instrument such methods with a call to __asan_init
// at the beginning in order to initialize our runtime before any access to
// the shadow memory.
// We cannot just ignore these methods, because they may call other
// instrumented functions.
if (F.getName().find(" load]") != std::string::npos) {
Function *AsanInitFunction =
declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
IRBuilder<> IRB(&F.front(), F.front().begin());
IRB.CreateCall(AsanInitFunction, {});
return true;
}
return false;
}
void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
// Generate code only when dynamic addressing is needed.
if (Mapping.Offset != kDynamicShadowSentinel)
return;
IRBuilder<> IRB(&F.front().front());
Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
kAsanShadowMemoryDynamicAddress, IntptrTy);
LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
}
void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
// Find the one possible call to llvm.localescape and pre-mark allocas passed
// to it as uninteresting. This assumes we haven't started processing allocas
// yet. This check is done up front because iterating the use list in
// isInterestingAlloca would be algorithmically slower.
assert(ProcessedAllocas.empty() && "must process localescape before allocas");
// Try to get the declaration of llvm.localescape. If it's not in the module,
// we can exit early.
if (!F.getParent()->getFunction("llvm.localescape")) return;
// Look for a call to llvm.localescape call in the entry block. It can't be in
// any other block.
for (Instruction &I : F.getEntryBlock()) {
IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
if (II && II->getIntrinsicID() == Intrinsic::localescape) {
// We found a call. Mark all the allocas passed in as uninteresting.
for (Value *Arg : II->arg_operands()) {
AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
assert(AI && AI->isStaticAlloca() &&
"non-static alloca arg to localescape");
ProcessedAllocas[AI] = false;
}
break;
}
}
}
bool AddressSanitizer::runOnFunction(Function &F) {
if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
if (F.getName().startswith("__asan_")) return false;
bool FunctionModified = false;
// If needed, insert __asan_init before checking for SanitizeAddress attr.
// This function needs to be called even if the function body is not
// instrumented.
if (maybeInsertAsanInitAtFunctionEntry(F))
FunctionModified = true;
// Leave if the function doesn't need instrumentation.
if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
initializeCallbacks(*F.getParent());
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
FunctionStateRAII CleanupObj(this);
maybeInsertDynamicShadowAtFunctionEntry(F);
// We can't instrument allocas used with llvm.localescape. Only static allocas
// can be passed to that intrinsic.
markEscapedLocalAllocas(F);
// We want to instrument every address only once per basic block (unless there
// are calls between uses).
SmallSet<Value *, 16> TempsToInstrument;
SmallVector<Instruction *, 16> ToInstrument;
SmallVector<Instruction *, 8> NoReturnCalls;
SmallVector<BasicBlock *, 16> AllBlocks;
SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
int NumAllocas = 0;
bool IsWrite;
unsigned Alignment;
uint64_t TypeSize;
const TargetLibraryInfo *TLI =
&getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
// Fill the set of memory operations to instrument.
for (auto &BB : F) {
AllBlocks.push_back(&BB);
TempsToInstrument.clear();
int NumInsnsPerBB = 0;
for (auto &Inst : BB) {
if (LooksLikeCodeInBug11395(&Inst)) return false;
Value *MaybeMask = nullptr;
if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
&Alignment, &MaybeMask)) {
if (ClOpt && ClOptSameTemp) {
// If we have a mask, skip instrumentation if we've already
// instrumented the full object. But don't add to TempsToInstrument
// because we might get another load/store with a different mask.
if (MaybeMask) {
if (TempsToInstrument.count(Addr))
continue; // We've seen this (whole) temp in the current BB.
} else {
if (!TempsToInstrument.insert(Addr).second)
continue; // We've seen this temp in the current BB.
}
}
} else if (ClInvalidPointerPairs &&
isInterestingPointerComparisonOrSubtraction(&Inst)) {
PointerComparisonsOrSubtracts.push_back(&Inst);
continue;
} else if (isa<MemIntrinsic>(Inst)) {
// ok, take it.
} else {
if (isa<AllocaInst>(Inst)) NumAllocas++;
CallSite CS(&Inst);
if (CS) {
// A call inside BB.
TempsToInstrument.clear();
if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
}
if (CallInst *CI = dyn_cast<CallInst>(&Inst))
maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
continue;
}
ToInstrument.push_back(&Inst);
NumInsnsPerBB++;
if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
}
}
bool UseCalls =
CompileKernel ||
(ClInstrumentationWithCallsThreshold >= 0 &&
ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
const DataLayout &DL = F.getParent()->getDataLayout();
ObjectSizeOpts ObjSizeOpts;
ObjSizeOpts.RoundToAlign = true;
ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), ObjSizeOpts);
// Instrument.
int NumInstrumented = 0;
for (auto Inst : ToInstrument) {
if (ClDebugMin < 0 || ClDebugMax < 0 ||
(NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
instrumentMop(ObjSizeVis, Inst, UseCalls,
F.getParent()->getDataLayout());
else
instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
}
NumInstrumented++;
}
FunctionStackPoisoner FSP(F, *this);
bool ChangedStack = FSP.runOnFunction();
// We must unpoison the stack before every NoReturn call (throw, _exit, etc).
// See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
for (auto CI : NoReturnCalls) {
IRBuilder<> IRB(CI);
IRB.CreateCall(AsanHandleNoReturnFunc, {});
}
for (auto Inst : PointerComparisonsOrSubtracts) {
instrumentPointerComparisonOrSubtraction(Inst);
NumInstrumented++;
}
if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
FunctionModified = true;
DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
<< F << "\n");
return FunctionModified;
}
// Workaround for bug 11395: we don't want to instrument stack in functions
// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
// FIXME: remove once the bug 11395 is fixed.
bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
if (LongSize != 32) return false;
CallInst *CI = dyn_cast<CallInst>(I);
if (!CI || !CI->isInlineAsm()) return false;
if (CI->getNumArgOperands() <= 5) return false;
// We have inline assembly with quite a few arguments.
return true;
}
void FunctionStackPoisoner::initializeCallbacks(Module &M) {
IRBuilder<> IRB(*C);
for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
std::string Suffix = itostr(i);
AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
IntptrTy, nullptr));
AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
}
if (ASan.UseAfterScope) {
AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
IntptrTy, IntptrTy, nullptr));
AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
IntptrTy, IntptrTy, nullptr));
}
for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
std::ostringstream Name;
Name << kAsanSetShadowPrefix;
Name << std::setw(2) << std::setfill('0') << std::hex << Val;
AsanSetShadowFunc[Val] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
}
AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
AsanAllocasUnpoisonFunc =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
}
void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
ArrayRef<uint8_t> ShadowBytes,
size_t Begin, size_t End,
IRBuilder<> &IRB,
Value *ShadowBase) {
if (Begin >= End)
return;
const size_t LargestStoreSizeInBytes =
std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
// Poison given range in shadow using larges store size with out leading and
// trailing zeros in ShadowMask. Zeros never change, so they need neither
// poisoning nor up-poisoning. Still we don't mind if some of them get into a
// middle of a store.
for (size_t i = Begin; i < End;) {
if (!ShadowMask[i]) {
assert(!ShadowBytes[i]);
++i;
continue;
}
size_t StoreSizeInBytes = LargestStoreSizeInBytes;
// Fit store size into the range.
while (StoreSizeInBytes > End - i)
StoreSizeInBytes /= 2;
// Minimize store size by trimming trailing zeros.
for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
while (j <= StoreSizeInBytes / 2)
StoreSizeInBytes /= 2;
}
uint64_t Val = 0;
for (size_t j = 0; j < StoreSizeInBytes; j++) {
if (IsLittleEndian)
Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
else
Val = (Val << 8) | ShadowBytes[i + j];
}
Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
IRB.CreateAlignedStore(
Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
i += StoreSizeInBytes;
}
}
void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
ArrayRef<uint8_t> ShadowBytes,
IRBuilder<> &IRB, Value *ShadowBase) {
copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
}
void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
ArrayRef<uint8_t> ShadowBytes,
size_t Begin, size_t End,
IRBuilder<> &IRB, Value *ShadowBase) {
assert(ShadowMask.size() == ShadowBytes.size());
size_t Done = Begin;
for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
if (!ShadowMask[i]) {
assert(!ShadowBytes[i]);
continue;
}
uint8_t Val = ShadowBytes[i];
if (!AsanSetShadowFunc[Val])
continue;
// Skip same values.
for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
}
if (j - i >= ClMaxInlinePoisoningSize) {
copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
IRB.CreateCall(AsanSetShadowFunc[Val],
{IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
ConstantInt::get(IntptrTy, j - i)});
Done = j;
}
}
copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
}
// Fake stack allocator (asan_fake_stack.h) has 11 size classes
// for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
static int StackMallocSizeClass(uint64_t LocalStackSize) {
assert(LocalStackSize <= kMaxStackMallocSize);
uint64_t MaxSize = kMinStackMallocSize;
for (int i = 0;; i++, MaxSize *= 2)
if (LocalStackSize <= MaxSize) return i;
llvm_unreachable("impossible LocalStackSize");
}
PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
Value *ValueIfTrue,
Instruction *ThenTerm,
Value *ValueIfFalse) {
PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
PHI->addIncoming(ValueIfFalse, CondBlock);
BasicBlock *ThenBlock = ThenTerm->getParent();
PHI->addIncoming(ValueIfTrue, ThenBlock);
return PHI;
}
Value *FunctionStackPoisoner::createAllocaForLayout(
IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
AllocaInst *Alloca;
if (Dynamic) {
Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
"MyAlloca");
} else {
Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
nullptr, "MyAlloca");
assert(Alloca->isStaticAlloca());
}
assert((ClRealignStack & (ClRealignStack - 1)) == 0);
size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
Alloca->setAlignment(FrameAlignment);
return IRB.CreatePointerCast(Alloca, IntptrTy);
}
void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
BasicBlock &FirstBB = *F.begin();
IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
DynamicAllocaLayout->setAlignment(32);
}
void FunctionStackPoisoner::processDynamicAllocas() {
if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
assert(DynamicAllocaPoisonCallVec.empty());
return;
}
// Insert poison calls for lifetime intrinsics for dynamic allocas.
for (const auto &APC : DynamicAllocaPoisonCallVec) {
assert(APC.InsBefore);
assert(APC.AI);
assert(ASan.isInterestingAlloca(*APC.AI));
assert(!APC.AI->isStaticAlloca());
IRBuilder<> IRB(APC.InsBefore);
poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
// Dynamic allocas will be unpoisoned unconditionally below in
// unpoisonDynamicAllocas.
// Flag that we need unpoison static allocas.
}
// Handle dynamic allocas.
createDynamicAllocasInitStorage();
for (auto &AI : DynamicAllocaVec)
handleDynamicAllocaCall(AI);
unpoisonDynamicAllocas();
}
void FunctionStackPoisoner::processStaticAllocas() {
if (AllocaVec.empty()) {
assert(StaticAllocaPoisonCallVec.empty());
return;
}
int StackMallocIdx = -1;
DebugLoc EntryDebugLocation;
if (auto SP = F.getSubprogram())
EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
Instruction *InsBefore = AllocaVec[0];
IRBuilder<> IRB(InsBefore);
IRB.SetCurrentDebugLocation(EntryDebugLocation);
// Make sure non-instrumented allocas stay in the entry block. Otherwise,
// debug info is broken, because only entry-block allocas are treated as
// regular stack slots.
auto InsBeforeB = InsBefore->getParent();
assert(InsBeforeB == &F.getEntryBlock());
for (auto *AI : StaticAllocasToMoveUp)
if (AI->getParent() == InsBeforeB)
AI->moveBefore(InsBefore);
// If we have a call to llvm.localescape, keep it in the entry block.
if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
SmallVector<ASanStackVariableDescription, 16> SVD;
SVD.reserve(AllocaVec.size());
for (AllocaInst *AI : AllocaVec) {
ASanStackVariableDescription D = {AI->getName().data(),
ASan.getAllocaSizeInBytes(*AI),
0,
AI->getAlignment(),
AI,
0,
0};
SVD.push_back(D);
}
// Minimal header size (left redzone) is 4 pointers,
// i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
size_t MinHeaderSize = ASan.LongSize / 2;
const ASanStackFrameLayout &L =
ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
// Build AllocaToSVDMap for ASanStackVariableDescription lookup.
DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
for (auto &Desc : SVD)
AllocaToSVDMap[Desc.AI] = &Desc;
// Update SVD with information from lifetime intrinsics.
for (const auto &APC : StaticAllocaPoisonCallVec) {
assert(APC.InsBefore);
assert(APC.AI);
assert(ASan.isInterestingAlloca(*APC.AI));
assert(APC.AI->isStaticAlloca());
ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
Desc.LifetimeSize = Desc.Size;
if (const DILocation *FnLoc = EntryDebugLocation.get()) {
if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
if (LifetimeLoc->getFile() == FnLoc->getFile())
if (unsigned Line = LifetimeLoc->getLine())
Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
}
}
}
auto DescriptionString = ComputeASanStackFrameDescription(SVD);
DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
uint64_t LocalStackSize = L.FrameSize;
bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
LocalStackSize <= kMaxStackMallocSize;
bool DoDynamicAlloca = ClDynamicAllocaStack;
// Don't do dynamic alloca or stack malloc if:
// 1) There is inline asm: too often it makes assumptions on which registers
// are available.
// 2) There is a returns_twice call (typically setjmp), which is
// optimization-hostile, and doesn't play well with introduced indirect
// register-relative calculation of local variable addresses.
DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
Value *StaticAlloca =
DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
Value *FakeStack;
Value *LocalStackBase;
if (DoStackMalloc) {
// void *FakeStack = __asan_option_detect_stack_use_after_return
// ? __asan_stack_malloc_N(LocalStackSize)
// : nullptr;
// void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
Value *UseAfterReturnIsEnabled =
IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
Constant::getNullValue(IRB.getInt32Ty()));
Instruction *Term =
SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
IRBuilder<> IRBIf(Term);
IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
StackMallocIdx = StackMallocSizeClass(LocalStackSize);
assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
Value *FakeStackValue =
IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
ConstantInt::get(IntptrTy, LocalStackSize));
IRB.SetInsertPoint(InsBefore);
IRB.SetCurrentDebugLocation(EntryDebugLocation);
FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
ConstantInt::get(IntptrTy, 0));
Value *NoFakeStack =
IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
IRBIf.SetInsertPoint(Term);
IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
Value *AllocaValue =
DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
IRB.SetInsertPoint(InsBefore);
IRB.SetCurrentDebugLocation(EntryDebugLocation);
LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
} else {
// void *FakeStack = nullptr;
// void *LocalStackBase = alloca(LocalStackSize);
FakeStack = ConstantInt::get(IntptrTy, 0);
LocalStackBase =
DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
}
// Replace Alloca instructions with base+offset.
for (const auto &Desc : SVD) {
AllocaInst *AI = Desc.AI;
Value *NewAllocaPtr = IRB.CreateIntToPtr(
IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
AI->getType());
replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
AI->replaceAllUsesWith(NewAllocaPtr);
}
// The left-most redzone has enough space for at least 4 pointers.
// Write the Magic value to redzone[0].
Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
BasePlus0);
// Write the frame description constant to redzone[1].
Value *BasePlus1 = IRB.CreateIntToPtr(
IRB.CreateAdd(LocalStackBase,
ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
IntptrPtrTy);
GlobalVariable *StackDescriptionGlobal =
createPrivateGlobalForString(*F.getParent(), DescriptionString,
/*AllowMerging*/ true);
Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
IRB.CreateStore(Description, BasePlus1);
// Write the PC to redzone[2].
Value *BasePlus2 = IRB.CreateIntToPtr(
IRB.CreateAdd(LocalStackBase,
ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
IntptrPtrTy);
IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
// Poison the stack red zones at the entry.
Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
// As mask we must use most poisoned case: red zones and after scope.
// As bytes we can use either the same or just red zones only.
copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
if (!StaticAllocaPoisonCallVec.empty()) {
const auto &ShadowInScope = GetShadowBytes(SVD, L);
// Poison static allocas near lifetime intrinsics.
for (const auto &APC : StaticAllocaPoisonCallVec) {
const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
assert(Desc.Offset % L.Granularity == 0);
size_t Begin = Desc.Offset / L.Granularity;
size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
IRBuilder<> IRB(APC.InsBefore);
copyToShadow(ShadowAfterScope,
APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
IRB, ShadowBase);
}
}
SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
SmallVector<uint8_t, 64> ShadowAfterReturn;
// (Un)poison the stack before all ret instructions.
for (auto Ret : RetVec) {
IRBuilder<> IRBRet(Ret);
// Mark the current frame as retired.
IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
BasePlus0);
if (DoStackMalloc) {
assert(StackMallocIdx >= 0);
// if FakeStack != 0 // LocalStackBase == FakeStack
// // In use-after-return mode, poison the whole stack frame.
// if StackMallocIdx <= 4
// // For small sizes inline the whole thing:
// memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
// **SavedFlagPtr(FakeStack) = 0
// else
// __asan_stack_free_N(FakeStack, LocalStackSize)
// else
// <This is not a fake stack; unpoison the redzones>
Value *Cmp =
IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
TerminatorInst *ThenTerm, *ElseTerm;
SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
IRBuilder<> IRBPoison(ThenTerm);
if (StackMallocIdx <= 4) {
int ClassSize = kMinStackMallocSize << StackMallocIdx;
ShadowAfterReturn.resize(ClassSize / L.Granularity,
kAsanStackUseAfterReturnMagic);
copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
ShadowBase);
Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
FakeStack,
ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
Value *SavedFlagPtr = IRBPoison.CreateLoad(
IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
IRBPoison.CreateStore(
Constant::getNullValue(IRBPoison.getInt8Ty()),
IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
} else {
// For larger frames call __asan_stack_free_*.
IRBPoison.CreateCall(
AsanStackFreeFunc[StackMallocIdx],
{FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
}
IRBuilder<> IRBElse(ElseTerm);
copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
} else {
copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
}
}
// We are done. Remove the old unused alloca instructions.
for (auto AI : AllocaVec) AI->eraseFromParent();
}
void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
IRBuilder<> &IRB, bool DoPoison) {
// For now just insert the call to ASan runtime.
Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
Value *SizeArg = ConstantInt::get(IntptrTy, Size);
IRB.CreateCall(
DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
{AddrArg, SizeArg});
}
// Handling llvm.lifetime intrinsics for a given %alloca:
// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
// invalid accesses) and unpoison it for llvm.lifetime.start (the memory
// could be poisoned by previous llvm.lifetime.end instruction, as the
// variable may go in and out of scope several times, e.g. in loops).
// (3) if we poisoned at least one %alloca in a function,
// unpoison the whole stack frame at function exit.
AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
// We're interested only in allocas we can handle.
return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
// See if we've already calculated (or started to calculate) alloca for a
// given value.
AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
if (I != AllocaForValue.end()) return I->second;
// Store 0 while we're calculating alloca for value V to avoid
// infinite recursion if the value references itself.
AllocaForValue[V] = nullptr;
AllocaInst *Res = nullptr;
if (CastInst *CI = dyn_cast<CastInst>(V))
Res = findAllocaForValue(CI->getOperand(0));
else if (PHINode *PN = dyn_cast<PHINode>(V)) {
for (Value *IncValue : PN->incoming_values()) {
// Allow self-referencing phi-nodes.
if (IncValue == PN) continue;
AllocaInst *IncValueAI = findAllocaForValue(IncValue);
// AI for incoming values should exist and should all be equal.
if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
return nullptr;
Res = IncValueAI;
}
} else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
Res = findAllocaForValue(EP->getPointerOperand());
} else {
DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
}
if (Res) AllocaForValue[V] = Res;
return Res;
}
void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
IRBuilder<> IRB(AI);
const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
Value *Zero = Constant::getNullValue(IntptrTy);
Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
// Since we need to extend alloca with additional memory to locate
// redzones, and OldSize is number of allocated blocks with
// ElementSize size, get allocated memory size in bytes by
// OldSize * ElementSize.
const unsigned ElementSize =
F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
Value *OldSize =
IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
ConstantInt::get(IntptrTy, ElementSize));
// PartialSize = OldSize % 32
Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
// Misalign = kAllocaRzSize - PartialSize;
Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
// PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
// AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
// Align is added to locate left redzone, PartialPadding for possible
// partial redzone and kAllocaRzSize for right redzone respectively.
Value *AdditionalChunkSize = IRB.CreateAdd(
ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
// Insert new alloca with new NewSize and Align params.
AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
NewAlloca->setAlignment(Align);
// NewAddress = Address + Align
Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
ConstantInt::get(IntptrTy, Align));
// Insert __asan_alloca_poison call for new created alloca.
IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
// Store the last alloca's address to DynamicAllocaLayout. We'll need this
// for unpoisoning stuff.
IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
// Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
AI->replaceAllUsesWith(NewAddressPtr);
// We are done. Erase old alloca from parent.
AI->eraseFromParent();
}
// isSafeAccess returns true if Addr is always inbounds with respect to its
// base object. For example, it is a field access or an array access with
// constant inbounds index.
bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
Value *Addr, uint64_t TypeSize) const {
SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
uint64_t Size = SizeOffset.first.getZExtValue();
int64_t Offset = SizeOffset.second.getSExtValue();
// Three checks are required to ensure safety:
// . Offset >= 0 (since the offset is given from the base ptr)
// . Size >= Offset (unsigned)
// . Size - Offset >= NeededSize (unsigned)
return Offset >= 0 && Size >= uint64_t(Offset) &&
Size - uint64_t(Offset) >= TypeSize / 8;
}
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