[msan] Don't delete MSanAtExitRecord

Summary:
Pre 2.27 libc can run same atexit handler twice
We will keep MSanAtExitRecord and reset fun to mark it as executed.

Fix PR40162

Reviewers: eugenis

Subscribers: jfb, jdoerfert, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D58221

llvm-svn: 354005

1 files changed, 5 insertions, 1 deletions

diff --git a/compiler-rt/lib/msan/msan_interceptors.cc b/compiler-rt/lib/msan/msan_interceptors.cc
index ba0599e333b..58b9c39e35c 100644
--- a/compiler-rt/lib/msan/msan_interceptors.cc
+++ b/compiler-rt/lib/msan/msan_interceptors.cc
@@ -1118,8 +1118,12 @@ void MSanAtExitWrapper() {
 void MSanCxaAtExitWrapper(void *arg) {
   UnpoisonParam(1);
   MSanAtExitRecord *r = (MSanAtExitRecord *)arg;
+  // libc before 2.27 had race which caused occasional double handler execution
+  // https://sourceware.org/ml/libc-alpha/2017-08/msg01204.html
+  if (!r->func)
+    return;
   r->func(r->arg);
-  InternalFree(r);
+  r->func = nullptr;
 }
 
 static int setup_at_exit_wrapper(void(*f)(), void *arg, void *dso);