[compiler-rt] [msan] Use `pthread_atfork` instead of interceptor (PR #75398)

[Vitaly Buka via llvm-commits]

https://github.com/vitalybuka updated https://github.com/llvm/llvm-project/pull/75398

>From 4d81ef26367fc6745bb3a8eac4fee9d213c2b7c6 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka at google.com>
Date: Wed, 13 Dec 2023 14:49:18 -0800
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Created using spr 1.3.4

[skip ci]
---
 compiler-rt/lib/hwasan/hwasan_linux.cpp          | 16 ++++++++++++++--
 compiler-rt/lib/hwasan/hwasan_thread.cpp         |  1 +
 .../TestCases/Posix/fork_threaded.c              |  2 --
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/compiler-rt/lib/hwasan/hwasan_linux.cpp b/compiler-rt/lib/hwasan/hwasan_linux.cpp
index f01fa42764134..3271a955e7ed1 100644
--- a/compiler-rt/lib/hwasan/hwasan_linux.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_linux.cpp
@@ -523,12 +523,24 @@ uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) {
 
 void HwasanInstallAtForkHandler() {
   auto before = []() {
-    HwasanAllocatorLock();
+    if (CAN_SANITIZE_LEAKS) {
+      __lsan::LockGlobal();
+    }
+    // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and lock the
+    // stuff we need.
+    __lsan::LockThreads();
+    __lsan::LockAllocator();
     StackDepotLockAll();
   };
   auto after = []() {
     StackDepotUnlockAll();
-    HwasanAllocatorUnlock();
+    // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and unlock
+    // the stuff we need.
+    __lsan::UnlockAllocator();
+    __lsan::UnlockThreads();
+    if (CAN_SANITIZE_LEAKS) {
+      __lsan::UnlockGlobal();
+    }
   };
   pthread_atfork(before, after, after);
 }
diff --git a/compiler-rt/lib/hwasan/hwasan_thread.cpp b/compiler-rt/lib/hwasan/hwasan_thread.cpp
index ce36547580e6e..3e14a718513d7 100644
--- a/compiler-rt/lib/hwasan/hwasan_thread.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_thread.cpp
@@ -68,6 +68,7 @@ void Thread::Init(uptr stack_buffer_start, uptr stack_buffer_size,
     }
     Print("Creating  : ");
   }
+  ClearShadowForThreadStackAndTLS();
 }
 
 void Thread::InitStackRingBuffer(uptr stack_buffer_start,
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 673d35346ba83..1b4a0ad6140db 100644
--- a/compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c
+++ b/compiler-rt/test/sanitizer_common/TestCases/Posix/fork_threaded.c
@@ -1,7 +1,5 @@
 // RUN: %clang -O0 %s -o %t && %env_tool_opts=die_after_fork=0 %run %t
 
-// UNSUPPORTED: hwasan
-
 // The test uses pthread barriers which are not available on Darwin.
 // UNSUPPORTED: darwin