forked from OSchip/llvm-project
372 lines
14 KiB
C++
372 lines
14 KiB
C++
//=== StackAddrEscapeChecker.cpp ----------------------------------*- C++ -*--//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file defines stack address leak checker, which checks if an invalid
|
|
// stack address is stored into a global or heap location. See CERT DCL30-C.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "ClangSACheckers.h"
|
|
#include "clang/AST/ExprCXX.h"
|
|
#include "clang/Basic/SourceManager.h"
|
|
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
|
|
#include "clang/StaticAnalyzer/Core/Checker.h"
|
|
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
|
|
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
|
|
#include "llvm/ADT/SmallString.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
using namespace clang;
|
|
using namespace ento;
|
|
|
|
namespace {
|
|
class StackAddrEscapeChecker
|
|
: public Checker<check::PreCall, check::PreStmt<ReturnStmt>,
|
|
check::EndFunction> {
|
|
mutable IdentifierInfo *dispatch_semaphore_tII;
|
|
mutable std::unique_ptr<BuiltinBug> BT_stackleak;
|
|
mutable std::unique_ptr<BuiltinBug> BT_returnstack;
|
|
mutable std::unique_ptr<BuiltinBug> BT_capturedstackasync;
|
|
mutable std::unique_ptr<BuiltinBug> BT_capturedstackret;
|
|
|
|
public:
|
|
enum CheckKind {
|
|
CK_StackAddrEscapeChecker,
|
|
CK_StackAddrAsyncEscapeChecker,
|
|
CK_NumCheckKinds
|
|
};
|
|
|
|
DefaultBool ChecksEnabled[CK_NumCheckKinds];
|
|
|
|
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
|
|
void checkPreStmt(const ReturnStmt *RS, CheckerContext &C) const;
|
|
void checkEndFunction(const ReturnStmt *RS, CheckerContext &Ctx) const;
|
|
|
|
private:
|
|
void checkReturnedBlockCaptures(const BlockDataRegion &B,
|
|
CheckerContext &C) const;
|
|
void checkAsyncExecutedBlockCaptures(const BlockDataRegion &B,
|
|
CheckerContext &C) const;
|
|
void EmitStackError(CheckerContext &C, const MemRegion *R,
|
|
const Expr *RetE) const;
|
|
bool isSemaphoreCaptured(const BlockDecl &B) const;
|
|
static SourceRange genName(raw_ostream &os, const MemRegion *R,
|
|
ASTContext &Ctx);
|
|
static SmallVector<const MemRegion *, 4>
|
|
getCapturedStackRegions(const BlockDataRegion &B, CheckerContext &C);
|
|
static bool isArcManagedBlock(const MemRegion *R, CheckerContext &C);
|
|
static bool isNotInCurrentFrame(const MemRegion *R, CheckerContext &C);
|
|
};
|
|
} // namespace
|
|
|
|
SourceRange StackAddrEscapeChecker::genName(raw_ostream &os, const MemRegion *R,
|
|
ASTContext &Ctx) {
|
|
// Get the base region, stripping away fields and elements.
|
|
R = R->getBaseRegion();
|
|
SourceManager &SM = Ctx.getSourceManager();
|
|
SourceRange range;
|
|
os << "Address of ";
|
|
|
|
// Check if the region is a compound literal.
|
|
if (const auto *CR = dyn_cast<CompoundLiteralRegion>(R)) {
|
|
const CompoundLiteralExpr *CL = CR->getLiteralExpr();
|
|
os << "stack memory associated with a compound literal "
|
|
"declared on line "
|
|
<< SM.getExpansionLineNumber(CL->getBeginLoc()) << " returned to caller";
|
|
range = CL->getSourceRange();
|
|
} else if (const auto *AR = dyn_cast<AllocaRegion>(R)) {
|
|
const Expr *ARE = AR->getExpr();
|
|
SourceLocation L = ARE->getBeginLoc();
|
|
range = ARE->getSourceRange();
|
|
os << "stack memory allocated by call to alloca() on line "
|
|
<< SM.getExpansionLineNumber(L);
|
|
} else if (const auto *BR = dyn_cast<BlockDataRegion>(R)) {
|
|
const BlockDecl *BD = BR->getCodeRegion()->getDecl();
|
|
SourceLocation L = BD->getBeginLoc();
|
|
range = BD->getSourceRange();
|
|
os << "stack-allocated block declared on line "
|
|
<< SM.getExpansionLineNumber(L);
|
|
} else if (const auto *VR = dyn_cast<VarRegion>(R)) {
|
|
os << "stack memory associated with local variable '" << VR->getString()
|
|
<< '\'';
|
|
range = VR->getDecl()->getSourceRange();
|
|
} else if (const auto *TOR = dyn_cast<CXXTempObjectRegion>(R)) {
|
|
QualType Ty = TOR->getValueType().getLocalUnqualifiedType();
|
|
os << "stack memory associated with temporary object of type '";
|
|
Ty.print(os, Ctx.getPrintingPolicy());
|
|
os << "'";
|
|
range = TOR->getExpr()->getSourceRange();
|
|
} else {
|
|
llvm_unreachable("Invalid region in ReturnStackAddressChecker.");
|
|
}
|
|
|
|
return range;
|
|
}
|
|
|
|
bool StackAddrEscapeChecker::isArcManagedBlock(const MemRegion *R,
|
|
CheckerContext &C) {
|
|
assert(R && "MemRegion should not be null");
|
|
return C.getASTContext().getLangOpts().ObjCAutoRefCount &&
|
|
isa<BlockDataRegion>(R);
|
|
}
|
|
|
|
bool StackAddrEscapeChecker::isNotInCurrentFrame(const MemRegion *R,
|
|
CheckerContext &C) {
|
|
const StackSpaceRegion *S = cast<StackSpaceRegion>(R->getMemorySpace());
|
|
return S->getStackFrame() != C.getStackFrame();
|
|
}
|
|
|
|
bool StackAddrEscapeChecker::isSemaphoreCaptured(const BlockDecl &B) const {
|
|
if (!dispatch_semaphore_tII)
|
|
dispatch_semaphore_tII = &B.getASTContext().Idents.get("dispatch_semaphore_t");
|
|
for (const auto &C : B.captures()) {
|
|
const auto *T = C.getVariable()->getType()->getAs<TypedefType>();
|
|
if (T && T->getDecl()->getIdentifier() == dispatch_semaphore_tII)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
SmallVector<const MemRegion *, 4>
|
|
StackAddrEscapeChecker::getCapturedStackRegions(const BlockDataRegion &B,
|
|
CheckerContext &C) {
|
|
SmallVector<const MemRegion *, 4> Regions;
|
|
BlockDataRegion::referenced_vars_iterator I = B.referenced_vars_begin();
|
|
BlockDataRegion::referenced_vars_iterator E = B.referenced_vars_end();
|
|
for (; I != E; ++I) {
|
|
SVal Val = C.getState()->getSVal(I.getCapturedRegion());
|
|
const MemRegion *Region = Val.getAsRegion();
|
|
if (Region && isa<StackSpaceRegion>(Region->getMemorySpace()))
|
|
Regions.push_back(Region);
|
|
}
|
|
return Regions;
|
|
}
|
|
|
|
void StackAddrEscapeChecker::EmitStackError(CheckerContext &C,
|
|
const MemRegion *R,
|
|
const Expr *RetE) const {
|
|
ExplodedNode *N = C.generateNonFatalErrorNode();
|
|
if (!N)
|
|
return;
|
|
if (!BT_returnstack)
|
|
BT_returnstack = llvm::make_unique<BuiltinBug>(
|
|
this, "Return of address to stack-allocated memory");
|
|
// Generate a report for this bug.
|
|
SmallString<128> buf;
|
|
llvm::raw_svector_ostream os(buf);
|
|
SourceRange range = genName(os, R, C.getASTContext());
|
|
os << " returned to caller";
|
|
auto report = llvm::make_unique<BugReport>(*BT_returnstack, os.str(), N);
|
|
report->addRange(RetE->getSourceRange());
|
|
if (range.isValid())
|
|
report->addRange(range);
|
|
C.emitReport(std::move(report));
|
|
}
|
|
|
|
void StackAddrEscapeChecker::checkAsyncExecutedBlockCaptures(
|
|
const BlockDataRegion &B, CheckerContext &C) const {
|
|
// There is a not-too-uncommon idiom
|
|
// where a block passed to dispatch_async captures a semaphore
|
|
// and then the thread (which called dispatch_async) is blocked on waiting
|
|
// for the completion of the execution of the block
|
|
// via dispatch_semaphore_wait. To avoid false-positives (for now)
|
|
// we ignore all the blocks which have captured
|
|
// a variable of the type "dispatch_semaphore_t".
|
|
if (isSemaphoreCaptured(*B.getDecl()))
|
|
return;
|
|
for (const MemRegion *Region : getCapturedStackRegions(B, C)) {
|
|
// The block passed to dispatch_async may capture another block
|
|
// created on the stack. However, there is no leak in this situaton,
|
|
// no matter if ARC or no ARC is enabled:
|
|
// dispatch_async copies the passed "outer" block (via Block_copy)
|
|
// and if the block has captured another "inner" block,
|
|
// the "inner" block will be copied as well.
|
|
if (isa<BlockDataRegion>(Region))
|
|
continue;
|
|
ExplodedNode *N = C.generateNonFatalErrorNode();
|
|
if (!N)
|
|
continue;
|
|
if (!BT_capturedstackasync)
|
|
BT_capturedstackasync = llvm::make_unique<BuiltinBug>(
|
|
this, "Address of stack-allocated memory is captured");
|
|
SmallString<128> Buf;
|
|
llvm::raw_svector_ostream Out(Buf);
|
|
SourceRange Range = genName(Out, Region, C.getASTContext());
|
|
Out << " is captured by an asynchronously-executed block";
|
|
auto Report =
|
|
llvm::make_unique<BugReport>(*BT_capturedstackasync, Out.str(), N);
|
|
if (Range.isValid())
|
|
Report->addRange(Range);
|
|
C.emitReport(std::move(Report));
|
|
}
|
|
}
|
|
|
|
void StackAddrEscapeChecker::checkReturnedBlockCaptures(
|
|
const BlockDataRegion &B, CheckerContext &C) const {
|
|
for (const MemRegion *Region : getCapturedStackRegions(B, C)) {
|
|
if (isArcManagedBlock(Region, C) || isNotInCurrentFrame(Region, C))
|
|
continue;
|
|
ExplodedNode *N = C.generateNonFatalErrorNode();
|
|
if (!N)
|
|
continue;
|
|
if (!BT_capturedstackret)
|
|
BT_capturedstackret = llvm::make_unique<BuiltinBug>(
|
|
this, "Address of stack-allocated memory is captured");
|
|
SmallString<128> Buf;
|
|
llvm::raw_svector_ostream Out(Buf);
|
|
SourceRange Range = genName(Out, Region, C.getASTContext());
|
|
Out << " is captured by a returned block";
|
|
auto Report =
|
|
llvm::make_unique<BugReport>(*BT_capturedstackret, Out.str(), N);
|
|
if (Range.isValid())
|
|
Report->addRange(Range);
|
|
C.emitReport(std::move(Report));
|
|
}
|
|
}
|
|
|
|
void StackAddrEscapeChecker::checkPreCall(const CallEvent &Call,
|
|
CheckerContext &C) const {
|
|
if (!ChecksEnabled[CK_StackAddrAsyncEscapeChecker])
|
|
return;
|
|
if (!Call.isGlobalCFunction("dispatch_after") &&
|
|
!Call.isGlobalCFunction("dispatch_async"))
|
|
return;
|
|
for (unsigned Idx = 0, NumArgs = Call.getNumArgs(); Idx < NumArgs; ++Idx) {
|
|
if (const BlockDataRegion *B = dyn_cast_or_null<BlockDataRegion>(
|
|
Call.getArgSVal(Idx).getAsRegion()))
|
|
checkAsyncExecutedBlockCaptures(*B, C);
|
|
}
|
|
}
|
|
|
|
void StackAddrEscapeChecker::checkPreStmt(const ReturnStmt *RS,
|
|
CheckerContext &C) const {
|
|
if (!ChecksEnabled[CK_StackAddrEscapeChecker])
|
|
return;
|
|
|
|
const Expr *RetE = RS->getRetValue();
|
|
if (!RetE)
|
|
return;
|
|
RetE = RetE->IgnoreParens();
|
|
|
|
SVal V = C.getSVal(RetE);
|
|
const MemRegion *R = V.getAsRegion();
|
|
if (!R)
|
|
return;
|
|
|
|
if (const BlockDataRegion *B = dyn_cast<BlockDataRegion>(R))
|
|
checkReturnedBlockCaptures(*B, C);
|
|
|
|
if (!isa<StackSpaceRegion>(R->getMemorySpace()) ||
|
|
isNotInCurrentFrame(R, C) || isArcManagedBlock(R, C))
|
|
return;
|
|
|
|
// Returning a record by value is fine. (In this case, the returned
|
|
// expression will be a copy-constructor, possibly wrapped in an
|
|
// ExprWithCleanups node.)
|
|
if (const ExprWithCleanups *Cleanup = dyn_cast<ExprWithCleanups>(RetE))
|
|
RetE = Cleanup->getSubExpr();
|
|
if (isa<CXXConstructExpr>(RetE) && RetE->getType()->isRecordType())
|
|
return;
|
|
|
|
// The CK_CopyAndAutoreleaseBlockObject cast causes the block to be copied
|
|
// so the stack address is not escaping here.
|
|
if (auto *ICE = dyn_cast<ImplicitCastExpr>(RetE)) {
|
|
if (isa<BlockDataRegion>(R) &&
|
|
ICE->getCastKind() == CK_CopyAndAutoreleaseBlockObject) {
|
|
return;
|
|
}
|
|
}
|
|
|
|
EmitStackError(C, R, RetE);
|
|
}
|
|
|
|
void StackAddrEscapeChecker::checkEndFunction(const ReturnStmt *RS,
|
|
CheckerContext &Ctx) const {
|
|
if (!ChecksEnabled[CK_StackAddrEscapeChecker])
|
|
return;
|
|
|
|
ProgramStateRef State = Ctx.getState();
|
|
|
|
// Iterate over all bindings to global variables and see if it contains
|
|
// a memory region in the stack space.
|
|
class CallBack : public StoreManager::BindingsHandler {
|
|
private:
|
|
CheckerContext &Ctx;
|
|
const StackFrameContext *CurSFC;
|
|
|
|
public:
|
|
SmallVector<std::pair<const MemRegion *, const MemRegion *>, 10> V;
|
|
|
|
CallBack(CheckerContext &CC) : Ctx(CC), CurSFC(CC.getStackFrame()) {}
|
|
|
|
bool HandleBinding(StoreManager &SMgr, Store S, const MemRegion *Region,
|
|
SVal Val) override {
|
|
|
|
if (!isa<GlobalsSpaceRegion>(Region->getMemorySpace()))
|
|
return true;
|
|
const MemRegion *VR = Val.getAsRegion();
|
|
if (VR && isa<StackSpaceRegion>(VR->getMemorySpace()) &&
|
|
!isArcManagedBlock(VR, Ctx) && !isNotInCurrentFrame(VR, Ctx))
|
|
V.emplace_back(Region, VR);
|
|
return true;
|
|
}
|
|
};
|
|
|
|
CallBack Cb(Ctx);
|
|
State->getStateManager().getStoreManager().iterBindings(State->getStore(),
|
|
Cb);
|
|
|
|
if (Cb.V.empty())
|
|
return;
|
|
|
|
// Generate an error node.
|
|
ExplodedNode *N = Ctx.generateNonFatalErrorNode(State);
|
|
if (!N)
|
|
return;
|
|
|
|
if (!BT_stackleak)
|
|
BT_stackleak = llvm::make_unique<BuiltinBug>(
|
|
this, "Stack address stored into global variable",
|
|
"Stack address was saved into a global variable. "
|
|
"This is dangerous because the address will become "
|
|
"invalid after returning from the function");
|
|
|
|
for (const auto &P : Cb.V) {
|
|
// Generate a report for this bug.
|
|
SmallString<128> Buf;
|
|
llvm::raw_svector_ostream Out(Buf);
|
|
SourceRange Range = genName(Out, P.second, Ctx.getASTContext());
|
|
Out << " is still referred to by the ";
|
|
if (isa<StaticGlobalSpaceRegion>(P.first->getMemorySpace()))
|
|
Out << "static";
|
|
else
|
|
Out << "global";
|
|
Out << " variable '";
|
|
const VarRegion *VR = cast<VarRegion>(P.first->getBaseRegion());
|
|
Out << *VR->getDecl()
|
|
<< "' upon returning to the caller. This will be a dangling reference";
|
|
auto Report = llvm::make_unique<BugReport>(*BT_stackleak, Out.str(), N);
|
|
if (Range.isValid())
|
|
Report->addRange(Range);
|
|
|
|
Ctx.emitReport(std::move(Report));
|
|
}
|
|
}
|
|
|
|
#define REGISTER_CHECKER(name) \
|
|
void ento::register##name(CheckerManager &Mgr) { \
|
|
StackAddrEscapeChecker *Chk = \
|
|
Mgr.registerChecker<StackAddrEscapeChecker>(); \
|
|
Chk->ChecksEnabled[StackAddrEscapeChecker::CK_##name] = true; \
|
|
}
|
|
|
|
REGISTER_CHECKER(StackAddrEscapeChecker)
|
|
REGISTER_CHECKER(StackAddrAsyncEscapeChecker)
|