[sanitizer] Avoid possible deadlock in child process after fork

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 or allocator 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. While calling alloc/dealloc routines after multi-threaded fork is not allowed,
most of modern allocators (Glibc, tcmalloc, jemalloc) are actually fork safe. Let's do the same
for sanitizers except TSan that has complex locking rules.

Differential Revision: https://reviews.llvm.org/D33325


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@304285 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 0 deletions

diff --git a/lib/lsan/lsan_interceptors.cc b/lib/lsan/lsan_interceptors.cc
index 9e39a7d19..b8cf6ae07 100644
--- a/lib/lsan/lsan_interceptors.cc
+++ b/lib/lsan/lsan_interceptors.cc
@@ -22,6 +22,7 @@
 #include "sanitizer_common/sanitizer_platform_interceptors.h"
 #include "sanitizer_common/sanitizer_platform_limits_posix.h"
 #include "sanitizer_common/sanitizer_posix.h"
+#include "sanitizer_common/sanitizer_stackdepot.h"
 #include "sanitizer_common/sanitizer_tls_get_addr.h"
 #include "lsan.h"
 #include "lsan_allocator.h"
@@ -97,6 +98,24 @@ INTERCEPTOR(void*, valloc, uptr size) {
 }
 #endif
 
+static void BeforeFork() {
+  LockAllocator();
+  StackDepotLockAll();
+}
+
+static void AfterFork() {
+  StackDepotUnlockAll();
+  UnlockAllocator();
+}
+
+INTERCEPTOR(int, fork, void) {
+  ENSURE_LSAN_INITED;
+  BeforeFork();
+  int pid = REAL(fork)();
+  AfterFork();
+  return pid;
+}
+
 #if SANITIZER_INTERCEPT_MEMALIGN
 INTERCEPTOR(void*, memalign, uptr alignment, uptr size) {
   ENSURE_LSAN_INITED;
@@ -336,6 +355,7 @@ void InitializeInterceptors() {
   LSAN_MAYBE_INTERCEPT_MALLOPT;
   INTERCEPT_FUNCTION(pthread_create);
   INTERCEPT_FUNCTION(pthread_join);
+  INTERCEPT_FUNCTION(fork);
 
   if (pthread_key_create(&g_thread_finalize_key, &thread_finalize)) {
     Report("LeakSanitizer: failed to create thread key.\n");