[compiler-rt] r182252 - [asan] Modify ASan metadata atomically.
Sergey Matveev
earthdok at google.com
Mon May 20 04:25:19 PDT 2013
Author: smatveev
Date: Mon May 20 06:25:18 2013
New Revision: 182252
URL: http://llvm.org/viewvc/llvm-project?rev=182252&view=rev
Log:
[asan] Modify ASan metadata atomically.
We need this to avoid races when ASan and LSan are used together.
Modified:
compiler-rt/trunk/lib/asan/asan_allocator2.cc
Modified: compiler-rt/trunk/lib/asan/asan_allocator2.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_allocator2.cc?rev=182252&r1=182251&r2=182252&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_allocator2.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_allocator2.cc Mon May 20 06:25:18 2013
@@ -265,7 +265,7 @@ struct QuarantineCallback {
void Recycle(AsanChunk *m) {
CHECK_EQ(m->chunk_state, CHUNK_QUARANTINE);
- m->chunk_state = CHUNK_AVAILABLE;
+ atomic_store((atomic_uint8_t*)m, CHUNK_AVAILABLE, memory_order_relaxed);
CHECK_NE(m->alloc_tid, kInvalidTid);
CHECK_NE(m->free_tid, kInvalidTid);
PoisonShadow(m->Beg(),
@@ -362,7 +362,6 @@ static void *Allocate(uptr size, uptr al
CHECK_LE(user_end, alloc_end);
uptr chunk_beg = user_beg - kChunkHeaderSize;
AsanChunk *m = reinterpret_cast<AsanChunk *>(chunk_beg);
- m->chunk_state = CHUNK_ALLOCATED;
m->alloc_type = alloc_type;
m->rz_log = rz_log;
u32 alloc_tid = t ? t->tid() : 0;
@@ -419,6 +418,8 @@ static void *Allocate(uptr size, uptr al
uptr fill_size = Min(size, (uptr)fl.max_malloc_fill_size);
REAL(memset)(res, fl.malloc_fill_byte, fill_size);
}
+ // Must be the last mutation of metadata in this function.
+ atomic_store((atomic_uint8_t *)m, CHUNK_ALLOCATED, memory_order_release);
ASAN_MALLOC_HOOK(res, size);
return res;
}
@@ -432,8 +433,9 @@ static void Deallocate(void *ptr, StackT
u8 old_chunk_state = CHUNK_ALLOCATED;
// Flip the chunk_state atomically to avoid race on double-free.
+ // Must be the first mutation of metadata in this function.
if (!atomic_compare_exchange_strong((atomic_uint8_t*)m, &old_chunk_state,
- CHUNK_QUARANTINE, memory_order_relaxed)) {
+ CHUNK_QUARANTINE, memory_order_acquire)) {
if (old_chunk_state == CHUNK_QUARANTINE)
ReportDoubleFree((uptr)ptr, stack);
else
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