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Move dereferences that crash when the iterator is invalid into the new CrashIfIteratorIsInvalid function in order to give more helpful stack traces.

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PiperOrigin-RevId: 915656842
Change-Id: I8542ce08c37d44f35a85e666eaf7eccd46132aef
This commit is contained in:
Evan Brown
2026-05-14 15:48:14 -07:00
committed by Copybara-Service
parent c20be0a44d
commit d936f59065
2 changed files with 34 additions and 19 deletions
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46
absl/container/internal/raw_hash_set.h
View File

@@ -1379,6 +1379,26 @@ constexpr bool SwisstableDebugEnabled() {
#endif
}
// Dereferences `ptr`. The function is named in order to provide a helpful error
// message when users see crashing stack traces. Note that this function is not
// guaranteed to crash when `ptr` is invalid if sanitizer mode is not enabled.
template <typename T>
T CrashIfIteratorIsInvalid(const T* ptr) {
// If the following line(s) crash, then it's likely that `ptr` is from a
// backing array that has been deallocated. If you see a crash here, it likely
// means that you are comparing an invalid iterator from a table that has
// rehashed, moved, or been destroyed. In such cases, it is often helpful to
// reproduce the issue with --config=asan and (assuming there's a crash here)
// examine the corresponding deallocation stack trace.
T ret = *ptr;
// Force a read with inline asm to make sure that a crash happens here, rather
// than later when the value is used.
#ifdef __clang__
asm("" : "+r"(ret));
#endif
return ret;
}
inline void AssertIsFull(const ctrl_t* ctrl, GenerationType generation,
const GenerationType* generation_ptr,
const char* operation) {
@@ -1396,20 +1416,21 @@ inline void AssertIsFull(const ctrl_t* ctrl, GenerationType generation,
operation);
}
if (SwisstableGenerationsEnabled()) {
if (ABSL_PREDICT_FALSE(generation != *generation_ptr)) {
if (ABSL_PREDICT_FALSE(generation !=
CrashIfIteratorIsInvalid(generation_ptr))) {
ABSL_RAW_LOG(FATAL,
"%s called on invalid iterator. The table could have "
"rehashed or moved since this iterator was initialized.",
operation);
}
if (ABSL_PREDICT_FALSE(!IsFull(*ctrl))) {
if (ABSL_PREDICT_FALSE(!IsFull(CrashIfIteratorIsInvalid(ctrl)))) {
ABSL_RAW_LOG(
FATAL,
"%s called on invalid iterator. The element was likely erased.",
operation);
}
} else {
if (ABSL_PREDICT_FALSE(!IsFull(*ctrl))) {
if (ABSL_PREDICT_FALSE(!IsFull(CrashIfIteratorIsInvalid(ctrl)))) {
ABSL_RAW_LOG(
FATAL,
"%s called on invalid iterator. The element might have been erased "
@@ -1425,20 +1446,15 @@ inline void AssertIsValidForComparison(const ctrl_t* ctrl,
GenerationType generation,
const GenerationType* generation_ptr) {
if (!SwisstableDebugEnabled()) return;
const bool ctrl_is_valid_for_comparison = [ctrl]() {
if (ctrl == nullptr) return true;
if (ctrl == DefaultIterControl()) return true;
// Note: if the following line crashes, then it's likely that `ctrl` is from
// a backing array that has been deallocated. If you see a crash here, it
// likely means that you are comparing an invalid iterator from a table that
// has rehashed, moved, or been destroyed.
return IsFull(*ctrl);
}();
const bool ctrl_is_valid_for_comparison =
ctrl == nullptr || ctrl == DefaultIterControl() ||
IsFull(CrashIfIteratorIsInvalid(ctrl));
if (SwisstableGenerationsEnabled()) {
if (ABSL_PREDICT_FALSE(generation != *generation_ptr)) {
if (ABSL_PREDICT_FALSE(generation !=
CrashIfIteratorIsInvalid(generation_ptr))) {
// Note: in the case of a rehash, we would expect to see a sanitizer crash
// above when `ctrl` is dereferenced so this assertion will only catch
// moved table cases, unless we're using a custom allocator that does not
// in CrashIfIteratorIsInvalid so this assertion will only catch moved
// table cases, unless we're using a custom allocator that does not
// deallocate the old backing array (e.g. an arena allocator).
ABSL_RAW_LOG(
FATAL,

7
absl/container/internal/raw_hash_set_test.cc
View File

@@ -2922,12 +2922,11 @@ TEST(TableDeathTest, InvalidIteratorAssertsSoo) {
// the control is static constant.
}
// Invalid iterator use can trigger use-after-free in asan/hwasan,
// use-of-uninitialized-value in msan, or invalidated iterator assertions.
// Invalid iterator use can trigger crashes or invalidated iterator assertions.
testing::Matcher<const std::string&> InvalidIteratorMatcher() {
return AnyOf(HasSubstr("invalidated iterator"), HasSubstr("Invalid iterator"),
HasSubstr("invalid iterator"), HasSubstr("use-after-free"),
HasSubstr("use-of-uninitialized-value"));
HasSubstr("invalid iterator"),
HasSubstr("CrashIfIteratorIsInvalid"));
}
TYPED_TEST(SooTest, IteratorInvalidAssertsEqualityOperator) {