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[Asan] Cleanup atomic usage in allocator 

There are no know bugs related to this, still it may fix some latent ones.
Main concerns with preexisting code:
1. Inconsistent atomic/non-atomic access to the same field.
2. Assumption that bitfield chunk_state is always the first byte without
    even taking into account endianness.

Reviewed By: morehouse

Differential Revision: https://reviews.llvm.org/D86917
This commit is contained in:
Vitaly Buka 2020-09-01 00:54:46 -07:00
parent 0f1be87e29
commit 8b8be6f38a
1 changed files with 66 additions and 43 deletions
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109
compiler-rt/lib/asan/asan_allocator.cpp
View File

@ -72,7 +72,7 @@ static const uptr kAllocBegMagic = 0xCC6E96B9;
struct ChunkHeader {
// 1-st 8 bytes.
u32 chunk_state : 8; // Must be first.
atomic_uint8_t chunk_state;
u32 alloc_tid : 24;
u32 free_tid : 24;
@ -88,7 +88,7 @@ struct ChunkHeader {
// align < 8 -> 0
// else -> log2(min(align, 512)) - 2
u32 user_requested_alignment_log : 3;
u32 alloc_context_id;
atomic_uint32_t alloc_context_id;
};
struct ChunkBase : ChunkHeader {
@ -140,8 +140,13 @@ struct QuarantineCallback {
}
void Recycle(AsanChunk *m) {
CHECK_EQ(m->chunk_state, CHUNK_QUARANTINE);
atomic_store((atomic_uint8_t*)m, CHUNK_AVAILABLE, memory_order_relaxed);
u8 old_chunk_state = CHUNK_QUARANTINE;
if (!atomic_compare_exchange_strong(&m->chunk_state, &old_chunk_state,
CHUNK_AVAILABLE,
memory_order_acquire)) {
CHECK_EQ(old_chunk_state, CHUNK_QUARANTINE);
}
CHECK_NE(m->alloc_tid, kInvalidTid);
CHECK_NE(m->free_tid, kInvalidTid);
PoisonShadow(m->Beg(),
@ -301,22 +306,25 @@ struct Allocator {
// housekeeping chunk, like TransferBatch. Start by assuming the former.
AsanChunk *ac = GetAsanChunk((void *)chunk);
uptr allocated_size = allocator.GetActuallyAllocatedSize((void *)ac);
uptr beg = ac->Beg();
uptr end = ac->Beg() + ac->UsedSize(true);
uptr chunk_end = chunk + allocated_size;
if (chunk < beg && beg < end && end <= chunk_end &&
ac->chunk_state == CHUNK_ALLOCATED) {
// Looks like a valid AsanChunk in use, poison redzones only.
PoisonShadow(chunk, beg - chunk, kAsanHeapLeftRedzoneMagic);
uptr end_aligned_down = RoundDownTo(end, SHADOW_GRANULARITY);
FastPoisonShadowPartialRightRedzone(
end_aligned_down, end - end_aligned_down,
chunk_end - end_aligned_down, kAsanHeapLeftRedzoneMagic);
} else {
// This is either not an AsanChunk or freed or quarantined AsanChunk.
// In either case, poison everything.
PoisonShadow(chunk, allocated_size, kAsanHeapLeftRedzoneMagic);
if (atomic_load(&ac->chunk_state, memory_order_acquire) ==
CHUNK_ALLOCATED) {
uptr beg = ac->Beg();
uptr end = ac->Beg() + ac->UsedSize(true);
uptr chunk_end = chunk + allocated_size;
if (chunk < beg && beg < end && end <= chunk_end) {
// Looks like a valid AsanChunk in use, poison redzones only.
PoisonShadow(chunk, beg - chunk, kAsanHeapLeftRedzoneMagic);
uptr end_aligned_down = RoundDownTo(end, SHADOW_GRANULARITY);
FastPoisonShadowPartialRightRedzone(
end_aligned_down, end - end_aligned_down,
chunk_end - end_aligned_down, kAsanHeapLeftRedzoneMagic);
return;
}
}
// This is either not an AsanChunk or freed or quarantined AsanChunk.
// In either case, poison everything.
PoisonShadow(chunk, allocated_size, kAsanHeapLeftRedzoneMagic);
}
void ReInitialize(const AllocatorOptions &options) {
@ -381,14 +389,17 @@ struct Allocator {
AsanChunk *right_chunk) {
// Prefer an allocated chunk over freed chunk and freed chunk
// over available chunk.
if (left_chunk->chunk_state != right_chunk->chunk_state) {
if (left_chunk->chunk_state == CHUNK_ALLOCATED)
u8 left_state = atomic_load(&left_chunk->chunk_state, memory_order_relaxed);
u8 right_state =
atomic_load(&right_chunk->chunk_state, memory_order_relaxed);
if (left_state != right_state) {
if (left_state == CHUNK_ALLOCATED)
return left_chunk;
if (right_chunk->chunk_state == CHUNK_ALLOCATED)
if (right_state == CHUNK_ALLOCATED)
return right_chunk;
if (left_chunk->chunk_state == CHUNK_QUARANTINE)
if (left_state == CHUNK_QUARANTINE)
return left_chunk;
if (right_chunk->chunk_state == CHUNK_QUARANTINE)
if (right_state == CHUNK_QUARANTINE)
return right_chunk;
}
// Same chunk_state: choose based on offset.
@ -403,9 +414,10 @@ struct Allocator {
bool UpdateAllocationStack(uptr addr, BufferedStackTrace *stack) {
AsanChunk *m = GetAsanChunkByAddr(addr);
if (!m) return false;
if (m->chunk_state != CHUNK_ALLOCATED) return false;
if (atomic_load(&m->chunk_state, memory_order_acquire) != CHUNK_ALLOCATED)
return false;
if (m->Beg() != addr) return false;
atomic_store((atomic_uint32_t *)&m->alloc_context_id, StackDepotPut(*stack),
atomic_store(&m->alloc_context_id, StackDepotPut(*stack),
memory_order_relaxed);
return true;
}
@ -524,7 +536,8 @@ struct Allocator {
}
m->user_requested_alignment_log = user_requested_alignment_log;
m->alloc_context_id = StackDepotPut(*stack);
atomic_store(&m->alloc_context_id, StackDepotPut(*stack),
memory_order_relaxed);
uptr size_rounded_down_to_granularity =
RoundDownTo(size, SHADOW_GRANULARITY);
@ -557,7 +570,7 @@ struct Allocator {
: __lsan::kDirectlyLeaked;
#endif
// Must be the last mutation of metadata in this function.
atomic_store((atomic_uint8_t *)m, CHUNK_ALLOCATED, memory_order_release);
atomic_store(&m->chunk_state, CHUNK_ALLOCATED, memory_order_release);
ASAN_MALLOC_HOOK(res, size);
return res;
}
@ -565,10 +578,10 @@ struct Allocator {
// Set quarantine flag if chunk is allocated, issue ASan error report on
// available and quarantined chunks. Return true on success, false otherwise.
bool AtomicallySetQuarantineFlagIfAllocated(AsanChunk *m, void *ptr,
BufferedStackTrace *stack) {
BufferedStackTrace *stack) {
u8 old_chunk_state = CHUNK_ALLOCATED;
// Flip the chunk_state atomically to avoid race on double-free.
if (!atomic_compare_exchange_strong((atomic_uint8_t *)m, &old_chunk_state,
if (!atomic_compare_exchange_strong(&m->chunk_state, &old_chunk_state,
CHUNK_QUARANTINE,
memory_order_acquire)) {
ReportInvalidFree(ptr, old_chunk_state, stack);
@ -582,7 +595,8 @@ struct Allocator {
// Expects the chunk to already be marked as quarantined by using
// AtomicallySetQuarantineFlagIfAllocated.
void QuarantineChunk(AsanChunk *m, void *ptr, BufferedStackTrace *stack) {
CHECK_EQ(m->chunk_state, CHUNK_QUARANTINE);
CHECK_EQ(atomic_load(&m->chunk_state, memory_order_relaxed),
CHUNK_QUARANTINE);
CHECK_GE(m->alloc_tid, 0);
if (SANITIZER_WORDSIZE == 64) // On 32-bits this resides in user area.
CHECK_EQ(m->free_tid, kInvalidTid);
@ -677,7 +691,7 @@ struct Allocator {
void *new_ptr = Allocate(new_size, 8, stack, FROM_MALLOC, true);
if (new_ptr) {
u8 chunk_state = m->chunk_state;
u8 chunk_state = atomic_load(&m->chunk_state, memory_order_acquire);
if (chunk_state != CHUNK_ALLOCATED)
ReportInvalidFree(old_ptr, chunk_state, stack);
CHECK_NE(REAL(memcpy), nullptr);
@ -774,7 +788,8 @@ struct Allocator {
uptr AllocationSize(uptr p) {
AsanChunk *m = GetAsanChunkByAddr(p);
if (!m) return 0;
if (m->chunk_state != CHUNK_ALLOCATED) return 0;
if (atomic_load(&m->chunk_state, memory_order_acquire) != CHUNK_ALLOCATED)
return 0;
if (m->Beg() != p) return 0;
return m->UsedSize();
}
@ -840,13 +855,16 @@ static AsanAllocator &get_allocator() {
}
bool AsanChunkView::IsValid() const {
return chunk_ && chunk_->chunk_state != CHUNK_AVAILABLE;
return chunk_ && atomic_load(&chunk_->chunk_state, memory_order_relaxed) !=
CHUNK_AVAILABLE;
}
bool AsanChunkView::IsAllocated() const {
return chunk_ && chunk_->chunk_state == CHUNK_ALLOCATED;
return chunk_ && atomic_load(&chunk_->chunk_state, memory_order_relaxed) ==
CHUNK_ALLOCATED;
}
bool AsanChunkView::IsQuarantined() const {
return chunk_ && chunk_->chunk_state == CHUNK_QUARANTINE;
return chunk_ && atomic_load(&chunk_->chunk_state, memory_order_relaxed) ==
CHUNK_QUARANTINE;
}
uptr AsanChunkView::Beg() const { return chunk_->Beg(); }
uptr AsanChunkView::End() const { return Beg() + UsedSize(); }
@ -867,7 +885,9 @@ static StackTrace GetStackTraceFromId(u32 id) {
return res;
}
u32 AsanChunkView::GetAllocStackId() const { return chunk_->alloc_context_id; }
u32 AsanChunkView::GetAllocStackId() const {
return atomic_load(&chunk_->alloc_context_id, memory_order_relaxed);
}
u32 AsanChunkView::GetFreeStackId() const { return chunk_->free_context_id; }
StackTrace AsanChunkView::GetAllocStack() const {
@ -1052,10 +1072,10 @@ void GetAllocatorGlobalRange(uptr *begin, uptr *end) {
uptr PointsIntoChunk(void* p) {
uptr addr = reinterpret_cast<uptr>(p);
__asan::AsanChunk *m = __asan::instance.GetAsanChunkByAddrFastLocked(addr);
if (!m) return 0;
uptr chunk = m->Beg();
if (m->chunk_state != __asan::CHUNK_ALLOCATED)
if (!m || atomic_load(&m->chunk_state, memory_order_acquire) !=
__asan::CHUNK_ALLOCATED)
return 0;
uptr chunk = m->Beg();
if (m->AddrIsInside(addr, /*locked_version=*/true))
return chunk;
if (IsSpecialCaseOfOperatorNew0(chunk, m->UsedSize(/*locked_version*/ true),
@ -1096,7 +1116,8 @@ LsanMetadata::LsanMetadata(uptr chunk) {
bool LsanMetadata::allocated() const {
__asan::AsanChunk *m = reinterpret_cast<__asan::AsanChunk *>(metadata_);
return m->chunk_state == __asan::CHUNK_ALLOCATED;
return atomic_load(&m->chunk_state, memory_order_relaxed) ==
__asan::CHUNK_ALLOCATED;
}
ChunkTag LsanMetadata::tag() const {
@ -1116,7 +1137,7 @@ uptr LsanMetadata::requested_size() const {
u32 LsanMetadata::stack_trace_id() const {
__asan::AsanChunk *m = reinterpret_cast<__asan::AsanChunk *>(metadata_);
return m->alloc_context_id;
return atomic_load(&m->alloc_context_id, memory_order_relaxed);
}
void ForEachChunk(ForEachChunkCallback callback, void *arg) {
@ -1127,7 +1148,9 @@ IgnoreObjectResult IgnoreObjectLocked(const void *p) {
uptr addr = reinterpret_cast<uptr>(p);
__asan::AsanChunk *m = __asan::instance.GetAsanChunkByAddr(addr);
if (!m) return kIgnoreObjectInvalid;
if ((m->chunk_state == __asan::CHUNK_ALLOCATED) && m->AddrIsInside(addr)) {
if ((atomic_load(&m->chunk_state, memory_order_acquire) ==
__asan::CHUNK_ALLOCATED) &&
m->AddrIsInside(addr)) {
if (m->lsan_tag == kIgnored)
return kIgnoreObjectAlreadyIgnored;
m->lsan_tag = __lsan::kIgnored;