[compiler-rt] e5ec87f - [asan] Print diagnostic if unlimited stack size detected (#133170)

[via llvm-commits]

Author: Thurston Dang
Date: 2025-03-27T08:55:36-07:00
New Revision: e5ec87f3b6816086563e39ac1f4c4f77064fba6d

URL: https://github.com/llvm/llvm-project/commit/e5ec87f3b6816086563e39ac1f4c4f77064fba6d
DIFF: https://github.com/llvm/llvm-project/commit/e5ec87f3b6816086563e39ac1f4c4f77064fba6d.diff

LOG: [asan] Print diagnostic if unlimited stack size detected (#133170)

This adds a diagnostic message if the stack size is unlimited. This would have simplified the diagnosis of https://github.com/google/sanitizers/issues/856#issuecomment-2747076811; we anticipate this may help diagnose future issues too.

Added: 
    

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

Removed: 
    


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diff  --git a/compiler-rt/lib/asan/asan_rtl.cpp b/compiler-rt/lib/asan/asan_rtl.cpp
index 19c6c210b564c..b3f6677a99cfb 100644
--- a/compiler-rt/lib/asan/asan_rtl.cpp
+++ b/compiler-rt/lib/asan/asan_rtl.cpp
@@ -451,6 +451,18 @@ static bool AsanInitInternal() {
 
   DisableCoreDumperIfNecessary();
 
+#if SANITIZER_POSIX
+  if (StackSizeIsUnlimited()) {
+    VPrintf(1,
+            "WARNING: Unlimited stack size detected. This may affect "
+            "compatibility with the shadow mappings.\n");
+    // MSan and TSan re-exec with a fixed size stack. We don't do that because
+    // it may break the program. InitializeShadowMemory() will, if needed,
+    // re-exec without ASLR, which solves most shadow mapping compatibility
+    // issues.
+  }
+#endif  // SANITIZER_POSIX
+
   InitializeShadowMemory();
 
   AsanTSDInit(PlatformTSDDtor);