[llvm-branch-commits] [compiler-rt] [asan] Install `pthread_atfork` (PR #75290)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

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

Author: Vitaly Buka (vitalybuka)

<details>
<summary>Changes</summary>

This prevents deadlocks in forked process
if parent had more then one running threads.


---
Full diff: https://github.com/llvm/llvm-project/pull/75290.diff


6 Files Affected:

- (modified) compiler-rt/lib/asan/asan_fuchsia.cpp (+2) 
- (modified) compiler-rt/lib/asan/asan_internal.h (+1) 
- (modified) compiler-rt/lib/asan/asan_posix.cpp (+24) 
- (modified) compiler-rt/lib/asan/asan_rtl.cpp (+2) 
- (modified) compiler-rt/lib/asan/asan_win.cpp (+2) 
- (modified) compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c (+1-1) 


``````````diff
diff --git a/compiler-rt/lib/asan/asan_fuchsia.cpp b/compiler-rt/lib/asan/asan_fuchsia.cpp
index 2b15504123bee..12625e9d75833 100644
--- a/compiler-rt/lib/asan/asan_fuchsia.cpp
+++ b/compiler-rt/lib/asan/asan_fuchsia.cpp
@@ -240,6 +240,8 @@ void FlushUnneededASanShadowMemory(uptr p, uptr size) {
 // So this doesn't install any atexit hook like on other platforms.
 void InstallAtExitCheckLeaks() {}
 
+void InstallAtForkHandler() {}
+
 }  // namespace __asan
 
 namespace __lsan {
diff --git a/compiler-rt/lib/asan/asan_internal.h b/compiler-rt/lib/asan/asan_internal.h
index 5b97e77882cd6..2944ebe213b5d 100644
--- a/compiler-rt/lib/asan/asan_internal.h
+++ b/compiler-rt/lib/asan/asan_internal.h
@@ -126,6 +126,7 @@ void *AsanDlSymNext(const char *sym);
 bool HandleDlopenInit();
 
 void InstallAtExitCheckLeaks();
+void InstallAtForkHandler();
 
 #define ASAN_ON_ERROR() \
   if (&__asan_on_error) \
diff --git a/compiler-rt/lib/asan/asan_posix.cpp b/compiler-rt/lib/asan/asan_posix.cpp
index e1f66641617cc..37fca8aea5151 100644
--- a/compiler-rt/lib/asan/asan_posix.cpp
+++ b/compiler-rt/lib/asan/asan_posix.cpp
@@ -148,6 +148,30 @@ void PlatformTSDDtor(void *tsd) {
 }
 #endif
 
+void InstallAtForkHandler() {
+  auto before = []() {
+    if (CAN_SANITIZE_LEAKS) {
+      __lsan::LockGlobal();
+    }
+    // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and do the
+    // job.
+    __lsan::LockThreads();
+    __lsan::LockAllocator();
+    StackDepotLockAll();
+  };
+  auto after = []() {
+    StackDepotUnlockAll();
+    // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and do the
+    // job.
+    __lsan::UnlockAllocator();
+    __lsan::UnlockThreads();
+    if (CAN_SANITIZE_LEAKS) {
+      __lsan::UnlockGlobal();
+    }
+  };
+  pthread_atfork(before, after, after);
+}
+
 void InstallAtExitCheckLeaks() {
   if (CAN_SANITIZE_LEAKS) {
     if (common_flags()->detect_leaks && common_flags()->leak_check_at_exit) {
diff --git a/compiler-rt/lib/asan/asan_rtl.cpp b/compiler-rt/lib/asan/asan_rtl.cpp
index b28f9f181239b..a61deed7382b0 100644
--- a/compiler-rt/lib/asan/asan_rtl.cpp
+++ b/compiler-rt/lib/asan/asan_rtl.cpp
@@ -493,6 +493,8 @@ static bool AsanInitInternal() {
     InstallAtExitCheckLeaks();
   }
 
+  InstallAtForkHandler();
+
 #if CAN_SANITIZE_UB
   __ubsan::InitAsPlugin();
 #endif
diff --git a/compiler-rt/lib/asan/asan_win.cpp b/compiler-rt/lib/asan/asan_win.cpp
index d5a30f471e2b0..f16ce677618e4 100644
--- a/compiler-rt/lib/asan/asan_win.cpp
+++ b/compiler-rt/lib/asan/asan_win.cpp
@@ -203,6 +203,8 @@ void InitializePlatformInterceptors() {
 
 void InstallAtExitCheckLeaks() {}
 
+void InstallAtForkHandler() {}
+
 void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
   UNIMPLEMENTED();
 }
diff --git a/compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c b/compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c
index 67d2993d11bf8..1a52702c5de8c 100644
--- a/compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c
+++ b/compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c
@@ -1,6 +1,6 @@
 // RUN: %clang -O0 %s -o %t && %env_tool_opts=die_after_fork=0 %run %t
 
-// UNSUPPORTED: asan, hwasan
+// UNSUPPORTED: hwasan
 
 // Forking in multithread environment is unsupported. However we already have
 // some workarounds, and will add more, so this is the test.

``````````

</details>


https://github.com/llvm/llvm-project/pull/75290