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llvm-project/compiler-rt/lib/asan/asan_descriptions.cc

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//===-- asan_descriptions.cc ------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// ASan functions for getting information about an address and/or printing it.
//===----------------------------------------------------------------------===//
#include "asan_descriptions.h"
#include "asan_mapping.h"
#include "asan_report.h"
#include "asan_stack.h"
#include "sanitizer_common/sanitizer_stackdepot.h"
namespace __asan {
AsanThreadIdAndName::AsanThreadIdAndName(AsanThreadContext *t) {
Init(t->tid, t->name);
}
AsanThreadIdAndName::AsanThreadIdAndName(u32 tid) {
if (tid == kInvalidTid) {
Init(tid, "");
} else {
asanThreadRegistry().CheckLocked();
AsanThreadContext *t = GetThreadContextByTidLocked(tid);
Init(tid, t->name);
}
}
void AsanThreadIdAndName::Init(u32 tid, const char *tname) {
int len = internal_snprintf(name, sizeof(name), "T%d", tid);
CHECK(((unsigned int)len) < sizeof(name));
if (tname[0] != '\0')
internal_snprintf(&name[len], sizeof(name) - len, " (%s)", tname);
}
void DescribeThread(AsanThreadContext *context) {
CHECK(context);
asanThreadRegistry().CheckLocked();
// No need to announce the main thread.
if (context->tid == 0 || context->announced) {
return;
}
context->announced = true;
InternalScopedString str(1024);
str.append("Thread %s", AsanThreadIdAndName(context).c_str());
if (context->parent_tid == kInvalidTid) {
str.append(" created by unknown thread\n");
Printf("%s", str.data());
return;
}
str.append(" created by %s here:\n",
AsanThreadIdAndName(context->parent_tid).c_str());
Printf("%s", str.data());
StackDepotGet(context->stack_id).Print();
// Recursively described parent thread if needed.
if (flags()->print_full_thread_history) {
AsanThreadContext *parent_context =
GetThreadContextByTidLocked(context->parent_tid);
DescribeThread(parent_context);
}
}
// Shadow descriptions
static bool GetShadowKind(uptr addr, ShadowKind *shadow_kind) {
CHECK(!AddrIsInMem(addr));
if (AddrIsInShadowGap(addr)) {
*shadow_kind = kShadowKindGap;
} else if (AddrIsInHighShadow(addr)) {
*shadow_kind = kShadowKindHigh;
} else if (AddrIsInLowShadow(addr)) {
*shadow_kind = kShadowKindLow;
} else {
CHECK(0 && "Address is not in memory and not in shadow?");
return false;
}
return true;
}
bool DescribeAddressIfShadow(uptr addr) {
ShadowAddressDescription descr;
if (!GetShadowAddressInformation(addr, &descr)) return false;
descr.Print();
return true;
}
bool GetShadowAddressInformation(uptr addr, ShadowAddressDescription *descr) {
if (AddrIsInMem(addr)) return false;
ShadowKind shadow_kind;
if (!GetShadowKind(addr, &shadow_kind)) return false;
if (shadow_kind != kShadowKindGap) descr->shadow_byte = *(u8 *)addr;
descr->addr = addr;
descr->kind = shadow_kind;
return true;
}
// Heap descriptions
static void GetAccessToHeapChunkInformation(ChunkAccess *descr,
AsanChunkView chunk, uptr addr,
uptr access_size) {
descr->bad_addr = addr;
if (chunk.AddrIsAtLeft(addr, access_size, &descr->offset)) {
descr->access_type = kAccessTypeLeft;
} else if (chunk.AddrIsAtRight(addr, access_size, &descr->offset)) {
descr->access_type = kAccessTypeRight;
if (descr->offset < 0) {
descr->bad_addr -= descr->offset;
descr->offset = 0;
}
} else if (chunk.AddrIsInside(addr, access_size, &descr->offset)) {
descr->access_type = kAccessTypeInside;
} else {
descr->access_type = kAccessTypeUnknown;
}
descr->chunk_begin = chunk.Beg();
descr->chunk_size = chunk.UsedSize();
descr->user_requested_alignment = chunk.UserRequestedAlignment();
descr->alloc_type = chunk.GetAllocType();
}
static void PrintHeapChunkAccess(uptr addr, const ChunkAccess &descr) {
Decorator d;
InternalScopedString str(4096);
str.append("%s", d.Location());
switch (descr.access_type) {
case kAccessTypeLeft:
str.append("%p is located %zd bytes to the left of",
(void *)descr.bad_addr, descr.offset);
break;
case kAccessTypeRight:
str.append("%p is located %zd bytes to the right of",
(void *)descr.bad_addr, descr.offset);
break;
case kAccessTypeInside:
str.append("%p is located %zd bytes inside of", (void *)descr.bad_addr,
descr.offset);
break;
case kAccessTypeUnknown:
str.append(
"%p is located somewhere around (this is AddressSanitizer bug!)",
(void *)descr.bad_addr);
}
str.append(" %zu-byte region [%p,%p)\n", descr.chunk_size,
(void *)descr.chunk_begin,
(void *)(descr.chunk_begin + descr.chunk_size));
str.append("%s", d.Default());
Printf("%s", str.data());
}
bool GetHeapAddressInformation(uptr addr, uptr access_size,
HeapAddressDescription *descr) {
AsanChunkView chunk = FindHeapChunkByAddress(addr);
if (!chunk.IsValid()) {
return false;
}
descr->addr = addr;
GetAccessToHeapChunkInformation(&descr->chunk_access, chunk, addr,
access_size);
CHECK_NE(chunk.AllocTid(), kInvalidTid);
descr->alloc_tid = chunk.AllocTid();
descr->alloc_stack_id = chunk.GetAllocStackId();
descr->free_tid = chunk.FreeTid();
if (descr->free_tid != kInvalidTid)
descr->free_stack_id = chunk.GetFreeStackId();
return true;
}
static StackTrace GetStackTraceFromId(u32 id) {
CHECK(id);
StackTrace res = StackDepotGet(id);
CHECK(res.trace);
return res;
}
bool DescribeAddressIfHeap(uptr addr, uptr access_size) {
HeapAddressDescription descr;
if (!GetHeapAddressInformation(addr, access_size, &descr)) {
Printf(
"AddressSanitizer can not describe address in more detail "
"(wild memory access suspected).\n");
return false;
}
descr.Print();
return true;
}
// Stack descriptions
bool GetStackAddressInformation(uptr addr, uptr access_size,
StackAddressDescription *descr) {
AsanThread *t = FindThreadByStackAddress(addr);
if (!t) return false;
descr->addr = addr;
descr->tid = t->tid();
// Try to fetch precise stack frame for this access.
AsanThread::StackFrameAccess access;
if (!t->GetStackFrameAccessByAddr(addr, &access)) {
descr->frame_descr = nullptr;
return true;
}
descr->offset = access.offset;
descr->access_size = access_size;
descr->frame_pc = access.frame_pc;
descr->frame_descr = access.frame_descr;
#if SANITIZER_PPC64V1
// On PowerPC64 ELFv1, the address of a function actually points to a
// three-doubleword data structure with the first field containing
// the address of the function's code.
descr->frame_pc = *reinterpret_cast<uptr *>(descr->frame_pc);
#endif
descr->frame_pc += 16;
return true;
}
static void PrintAccessAndVarIntersection(const StackVarDescr &var, uptr addr,
uptr access_size, uptr prev_var_end,
uptr next_var_beg) {
uptr var_end = var.beg + var.size;
uptr addr_end = addr + access_size;
const char *pos_descr = nullptr;
// If the variable [var.beg, var_end) is the nearest variable to the
// current memory access, indicate it in the log.
if (addr >= var.beg) {
if (addr_end <= var_end)
pos_descr = "is inside"; // May happen if this is a use-after-return.
else if (addr < var_end)
pos_descr = "partially overflows";
else if (addr_end <= next_var_beg &&
next_var_beg - addr_end >= addr - var_end)
pos_descr = "overflows";
} else {
if (addr_end > var.beg)
pos_descr = "partially underflows";
else if (addr >= prev_var_end && addr - prev_var_end >= var.beg - addr_end)
pos_descr = "underflows";
}
InternalScopedString str(1024);
str.append(" [%zd, %zd)", var.beg, var_end);
// Render variable name.
str.append(" '");
for (uptr i = 0; i < var.name_len; ++i) {
str.append("%c", var.name_pos[i]);
}
str.append("'");
if (var.line > 0) {
str.append(" (line %d)", var.line);
}
if (pos_descr) {
Decorator d;
// FIXME: we may want to also print the size of the access here,
// but in case of accesses generated by memset it may be confusing.
str.append("%s <== Memory access at offset %zd %s this variable%s\n",
d.Location(), addr, pos_descr, d.Default());
} else {
str.append("\n");
}
Printf("%s", str.data());
}
bool DescribeAddressIfStack(uptr addr, uptr access_size) {
StackAddressDescription descr;
if (!GetStackAddressInformation(addr, access_size, &descr)) return false;
descr.Print();
return true;
}
// Global descriptions
static void DescribeAddressRelativeToGlobal(uptr addr, uptr access_size,
const __asan_global &g) {
InternalScopedString str(4096);
Decorator d;
str.append("%s", d.Location());
if (addr < g.beg) {
str.append("%p is located %zd bytes to the left", (void *)addr,
g.beg - addr);
} else if (addr + access_size > g.beg + g.size) {
if (addr < g.beg + g.size) addr = g.beg + g.size;
str.append("%p is located %zd bytes to the right", (void *)addr,
addr - (g.beg + g.size));
} else {
// Can it happen?
str.append("%p is located %zd bytes inside", (void *)addr, addr - g.beg);
}
str.append(" of global variable '%s' defined in '",
MaybeDemangleGlobalName(g.name));
PrintGlobalLocation(&str, g);
str.append("' (0x%zx) of size %zu\n", g.beg, g.size);
str.append("%s", d.Default());
PrintGlobalNameIfASCII(&str, g);
Printf("%s", str.data());
}
bool GetGlobalAddressInformation(uptr addr, uptr access_size,
GlobalAddressDescription *descr) {
descr->addr = addr;
int globals_num = GetGlobalsForAddress(addr, descr->globals, descr->reg_sites,
ARRAY_SIZE(descr->globals));
descr->size = globals_num;
descr->access_size = access_size;
return globals_num != 0;
}
bool DescribeAddressIfGlobal(uptr addr, uptr access_size,
const char *bug_type) {
GlobalAddressDescription descr;
if (!GetGlobalAddressInformation(addr, access_size, &descr)) return false;
descr.Print(bug_type);
return true;
}
void ShadowAddressDescription::Print() const {
Printf("Address %p is located in the %s area.\n", addr, ShadowNames[kind]);
}
void GlobalAddressDescription::Print(const char *bug_type) const {
for (int i = 0; i < size; i++) {
DescribeAddressRelativeToGlobal(addr, access_size, globals[i]);
if (bug_type &&
0 == internal_strcmp(bug_type, "initialization-order-fiasco") &&
reg_sites[i]) {
Printf(" registered at:\n");
StackDepotGet(reg_sites[i]).Print();
}
}
}
bool GlobalAddressDescription::PointsInsideTheSameVariable(
const GlobalAddressDescription &other) const {
if (size == 0 || other.size == 0) return false;
for (uptr i = 0; i < size; i++) {
const __asan_global &a = globals[i];
for (uptr j = 0; j < other.size; j++) {
const __asan_global &b = other.globals[j];
if (a.beg == b.beg &&
a.beg <= addr &&
b.beg <= other.addr &&
(addr + access_size) < (a.beg + a.size) &&
(other.addr + other.access_size) < (b.beg + b.size))
return true;
}
}
return false;
}
void StackAddressDescription::Print() const {
Decorator d;
Printf("%s", d.Location());
Printf("Address %p is located in stack of thread %s", addr,
AsanThreadIdAndName(tid).c_str());
if (!frame_descr) {
Printf("%s\n", d.Default());
return;
}
Printf(" at offset %zu in frame%s\n", offset, d.Default());
// Now we print the frame where the alloca has happened.
// We print this frame as a stack trace with one element.
// The symbolizer may print more than one frame if inlining was involved.
// The frame numbers may be different than those in the stack trace printed
// previously. That's unfortunate, but I have no better solution,
// especially given that the alloca may be from entirely different place
// (e.g. use-after-scope, or different thread's stack).
Printf("%s", d.Default());
StackTrace alloca_stack(&frame_pc, 1);
alloca_stack.Print();
InternalMmapVector<StackVarDescr> vars;
vars.reserve(16);
if (!ParseFrameDescription(frame_descr, &vars)) {
Printf(
"AddressSanitizer can't parse the stack frame "
"descriptor: |%s|\n",
frame_descr);
// 'addr' is a stack address, so return true even if we can't parse frame
return;
}
uptr n_objects = vars.size();
// Report the number of stack objects.
Printf(" This frame has %zu object(s):\n", n_objects);
// Report all objects in this frame.
for (uptr i = 0; i < n_objects; i++) {
uptr prev_var_end = i ? vars[i - 1].beg + vars[i - 1].size : 0;
uptr next_var_beg = i + 1 < n_objects ? vars[i + 1].beg : ~(0UL);
PrintAccessAndVarIntersection(vars[i], offset, access_size, prev_var_end,
next_var_beg);
}
Printf(
"HINT: this may be a false positive if your program uses "
"some custom stack unwind mechanism, swapcontext or vfork\n");
if (SANITIZER_WINDOWS)
Printf(" (longjmp, SEH and C++ exceptions *are* supported)\n");
else
Printf(" (longjmp and C++ exceptions *are* supported)\n");
DescribeThread(GetThreadContextByTidLocked(tid));
}
void HeapAddressDescription::Print() const {
PrintHeapChunkAccess(addr, chunk_access);
asanThreadRegistry().CheckLocked();
AsanThreadContext *alloc_thread = GetThreadContextByTidLocked(alloc_tid);
StackTrace alloc_stack = GetStackTraceFromId(alloc_stack_id);
Decorator d;
AsanThreadContext *free_thread = nullptr;
if (free_tid != kInvalidTid) {
free_thread = GetThreadContextByTidLocked(free_tid);
Printf("%sfreed by thread %s here:%s\n", d.Allocation(),
AsanThreadIdAndName(free_thread).c_str(), d.Default());
StackTrace free_stack = GetStackTraceFromId(free_stack_id);
free_stack.Print();
Printf("%spreviously allocated by thread %s here:%s\n", d.Allocation(),
AsanThreadIdAndName(alloc_thread).c_str(), d.Default());
} else {
Printf("%sallocated by thread %s here:%s\n", d.Allocation(),
AsanThreadIdAndName(alloc_thread).c_str(), d.Default());
}
alloc_stack.Print();
DescribeThread(GetCurrentThread());
if (free_thread) DescribeThread(free_thread);
DescribeThread(alloc_thread);
}
AddressDescription::AddressDescription(uptr addr, uptr access_size,
bool shouldLockThreadRegistry) {
if (GetShadowAddressInformation(addr, &data.shadow)) {
data.kind = kAddressKindShadow;
return;
}
if (GetHeapAddressInformation(addr, access_size, &data.heap)) {
data.kind = kAddressKindHeap;
return;
}
bool isStackMemory = false;
if (shouldLockThreadRegistry) {
ThreadRegistryLock l(&asanThreadRegistry());
isStackMemory = GetStackAddressInformation(addr, access_size, &data.stack);
} else {
isStackMemory = GetStackAddressInformation(addr, access_size, &data.stack);
}
if (isStackMemory) {
data.kind = kAddressKindStack;
return;
}
if (GetGlobalAddressInformation(addr, access_size, &data.global)) {
data.kind = kAddressKindGlobal;
return;
}
data.kind = kAddressKindWild;
addr = 0;
}
void PrintAddressDescription(uptr addr, uptr access_size,
const char *bug_type) {
ShadowAddressDescription shadow_descr;
if (GetShadowAddressInformation(addr, &shadow_descr)) {
shadow_descr.Print();
return;
}
GlobalAddressDescription global_descr;
if (GetGlobalAddressInformation(addr, access_size, &global_descr)) {
global_descr.Print(bug_type);
return;
}
StackAddressDescription stack_descr;
if (GetStackAddressInformation(addr, access_size, &stack_descr)) {
stack_descr.Print();
return;
}
HeapAddressDescription heap_descr;
if (GetHeapAddressInformation(addr, access_size, &heap_descr)) {
heap_descr.Print();
return;
}
// We exhausted our possibilities. Bail out.
Printf(
"AddressSanitizer can not describe address in more detail "
"(wild memory access suspected).\n");
}
} // namespace __asan
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