[compiler-rt] 2eda2e0 - [HWASAN] Prevent crashes on thread exit

[Vitaly Buka via llvm-commits]

Author: Vitaly Buka
Date: 2023-05-11T16:15:06-07:00
New Revision: 2eda2e013830537800b68c9217fc14ea7704e618

URL: https://github.com/llvm/llvm-project/commit/2eda2e013830537800b68c9217fc14ea7704e618
DIFF: https://github.com/llvm/llvm-project/commit/2eda2e013830537800b68c9217fc14ea7704e618.diff

LOG: [HWASAN] Prevent crashes on thread exit

I can't figure out how to reproduce this for test, but I see the case on
random binaries.

The known issue is with GLIBC, others may have a workaround, e.g. Bionic,
https://cs.android.com/android/platform/superproject/+/master:bionic/libc/bionic/pthread_exit.cpp;l=149
see signals blocked above.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D150401

Added: 
    

Modified: 
    compiler-rt/lib/hwasan/hwasan_linux.cpp

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/hwasan/hwasan_linux.cpp b/compiler-rt/lib/hwasan/hwasan_linux.cpp
index abf92d290c84..6f5e9432974e 100644
--- a/compiler-rt/lib/hwasan/hwasan_linux.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_linux.cpp
@@ -302,8 +302,15 @@ extern "C" void __hwasan_thread_exit() {
   Thread *t = GetCurrentThread();
   // Make sure that signal handler can not see a stale current thread pointer.
   atomic_signal_fence(memory_order_seq_cst);
-  if (t)
+  if (t) {
+    // Block async signals on the thread as the handler can be instrumented.
+    // After this point instrumented code can't access essential data from TLS
+    // and will crash.
+    // Bionic already calls __hwasan_thread_exit with blocked signals.
+    if (SANITIZER_GLIBC)
+      BlockSignals();
     hwasanThreadList().ReleaseThread(t);
+  }
 }
 
 #  if HWASAN_WITH_INTERCEPTORS