[compiler-rt] [asan] Prevent printing invalid parent thread (PR #111916)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Vitaly Buka (vitalybuka)

<details>
<summary>Changes</summary>

By default reuse can happend only after
`UINT32_MAX` threads, so it's almost NFC.


---
Full diff: https://github.com/llvm/llvm-project/pull/111916.diff


1 Files Affected:

- (modified) compiler-rt/lib/asan/asan_descriptions.cpp (+4-1) 


``````````diff
diff --git a/compiler-rt/lib/asan/asan_descriptions.cpp b/compiler-rt/lib/asan/asan_descriptions.cpp
index 1c2f20a76343bb..778e134f1cf2a5 100644
--- a/compiler-rt/lib/asan/asan_descriptions.cpp
+++ b/compiler-rt/lib/asan/asan_descriptions.cpp
@@ -63,7 +63,10 @@ void DescribeThread(AsanThreadContext *context) {
   if (flags()->print_full_thread_history) {
     AsanThreadContext *parent_context =
         GetThreadContextByTidLocked(context->parent_tid);
-    DescribeThread(parent_context);
+    // `context->parent_tid` may point to reused slot, double check, `unique_id`
+    // of new user will always be greater then the child.
+    if (context->unique_id > parent_context->unique_id)
+      DescribeThread(parent_context);
   }
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/111916