[compiler-rt] 4a04fca - [compiler-rt][asan] Fix for flaky asan check (#88177)

[via llvm-commits]

Author: PiJoules
Date: 2024-04-09T15:39:05-07:00
New Revision: 4a04fca9e2f936264bccba58081893c6703de7ec

URL: https://github.com/llvm/llvm-project/commit/4a04fca9e2f936264bccba58081893c6703de7ec
DIFF: https://github.com/llvm/llvm-project/commit/4a04fca9e2f936264bccba58081893c6703de7ec.diff

LOG: [compiler-rt][asan] Fix for flaky asan check (#88177)

This fixes https://github.com/llvm/llvm-project/issues/87324.

We haven't been able to come up with a minimal reproducer but we can
reliabely avoid this failure with the following fix. Prior to the
GetGlobalLowLevelAllocator change, the old LowLevelAllocator aquired a
lock associated with it preventing that specific allocator from being
accessed at the same time by many threads. With the
GetGlobalLowLevelAllocator change, I had accidentally replaced it but
not taken into account the lock, so we can have a data race if the
allocator is used at any point while a thread is being created. The
global allocator can be used for flag parsing or registering asan
globals.

Added: 
    

Modified: 
    compiler-rt/lib/asan/asan_thread.cpp

Removed: 
    


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diff  --git a/compiler-rt/lib/asan/asan_thread.cpp b/compiler-rt/lib/asan/asan_thread.cpp
index 8798968947e82e..480a423952e8f3 100644
--- a/compiler-rt/lib/asan/asan_thread.cpp
+++ b/compiler-rt/lib/asan/asan_thread.cpp
@@ -44,10 +44,15 @@ static ThreadRegistry *asan_thread_registry;
 static ThreadArgRetval *thread_data;
 
 static Mutex mu_for_thread_context;
+// TODO(leonardchan@): It should be possible to make LowLevelAllocator
+// threadsafe and consolidate this one into the GlobalLoweLevelAllocator.
+// We should be able to do something similar to what's in
+// sanitizer_stack_store.cpp.
+static LowLevelAllocator allocator_for_thread_context;
 
 static ThreadContextBase *GetAsanThreadContext(u32 tid) {
   Lock lock(&mu_for_thread_context);
-  return new (GetGlobalLowLevelAllocator()) AsanThreadContext(tid);
+  return new (allocator_for_thread_context) AsanThreadContext(tid);
 }
 
 static void InitThreads() {