[PATCH] D33325: [asan] Avoid possible deadlock in child process after fork

[Maxim Ostapenko via Phabricator via llvm-commits]

m.ostapenko created this revision.
m.ostapenko added a project: Sanitizers.
Herald added a subscriber: kubamracek.

This patch addresses https://github.com/google/sanitizers/issues/774
When we fork a multi-threaded process it's possible to deadlock if some thread acquired StackDepot internal lock just before fork. In this case the lock will never be released in child process causing deadlock on following memory alloc/dealloc routine.


Repository:
  rL LLVM

https://reviews.llvm.org/D33325

Files:
  lib/asan/asan_interceptors.cc


Index: lib/asan/asan_interceptors.cc
===================================================================
--- lib/asan/asan_interceptors.cc
+++ lib/asan/asan_interceptors.cc
@@ -22,6 +22,7 @@
 #include "asan_stats.h"
 #include "asan_suppressions.h"
 #include "lsan/lsan_common.h"
+#include "sanitizer_common/sanitizer_stackdepot.h"
 #include "sanitizer_common/sanitizer_libc.h"
 
 #if SANITIZER_POSIX
@@ -711,11 +712,21 @@
 #endif  // ASAN_INTERCEPT___CXA_ATEXIT
 
 #if ASAN_INTERCEPT_FORK
+static void BeforeFork() {
+  StackDepotLockAll();
+}
+
+static void AfterFork() {
+  StackDepotUnlockAll();
+}
+
 INTERCEPTOR(int, fork, void) {
   ENSURE_ASAN_INITED();
+  BeforeFork();
   if (common_flags()->coverage) CovBeforeFork();
   int pid = REAL(fork)();
   if (common_flags()->coverage) CovAfterFork(pid);
+  AfterFork();
   return pid;
 }
 #endif  // ASAN_INTERCEPT_FORK


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