[compiler-rt] [ASan][Windows] Synchronizing ASAN init on Windows (PR #71833)
Zack Johnson via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 16 07:14:27 PST 2023
https://github.com/zacklj89 updated https://github.com/llvm/llvm-project/pull/71833
>From 441bebdb0be456eba70a24f43cbd9a0d1c8b0b62 Mon Sep 17 00:00:00 2001
From: Zachary Johnson <zajohnson at microsoft.com>
Date: Thu, 9 Nov 2023 15:13:24 -0500
Subject: [PATCH 1/2] [asan] Fixing initialization synchronization on Windows
---
compiler-rt/lib/asan/asan_internal.h | 13 +++++++
compiler-rt/lib/asan/asan_rtl.cpp | 51 ++++++++++++++++++++++++----
compiler-rt/lib/asan/asan_thread.cpp | 23 +++++++++++++
3 files changed, 81 insertions(+), 6 deletions(-)
diff --git a/compiler-rt/lib/asan/asan_internal.h b/compiler-rt/lib/asan/asan_internal.h
index e2b1e9800f5be62..f98cbd5da96bc8c 100644
--- a/compiler-rt/lib/asan/asan_internal.h
+++ b/compiler-rt/lib/asan/asan_internal.h
@@ -130,6 +130,19 @@ void InstallAtExitCheckLeaks();
if (&__asan_on_error) \
__asan_on_error()
+// Depending on the loading thread and when ASAN is loaded on Windows,
+// race conditions can appear causing incorrect states or internal check
+// failures.
+//
+// From a multithreaded managed environment, if an ASAN instrumented dll
+// is loading on a spawned thread, an intercepted function may be called on
+// multiple threads while ASAN is still in the process of initialization. This
+// can also cause the ASAN thread registry to create the "main" thread after
+// another thread, resulting in a TID != 0.
+//
+// Two threads can also race to initialize ASAN, resulting in either incorrect
+// state or internal check failures for init already running.
+//
bool AsanInited();
bool AsanInitIsRunning(); // Used to avoid infinite recursion in __asan_init().
extern bool replace_intrin_cached;
diff --git a/compiler-rt/lib/asan/asan_rtl.cpp b/compiler-rt/lib/asan/asan_rtl.cpp
index d1e7856973b43b3..ade77d68f36d56d 100644
--- a/compiler-rt/lib/asan/asan_rtl.cpp
+++ b/compiler-rt/lib/asan/asan_rtl.cpp
@@ -71,16 +71,54 @@ static void CheckUnwind() {
}
// -------------------------- Globals --------------------- {{{1
-static int asan_inited = 0;
-static int asan_init_is_running = 0;
+#if SANITIZER_WINDOWS
+atomic_uint8_t asan_inited{0};
+atomic_uint8_t asan_init_is_running{0};
+#else
+int asan_inited = 0;
+int asan_init_is_running = 0;
+#endif
-void SetAsanInited(u32 val) { asan_inited = val; }
+void SetAsanInited(u32 val) {
+#if SANITIZER_WINDOWS
+ atomic_store(&asan_inited, val, memory_order_release);
+#else
+ asan_inited = val;
+#endif
+}
-void SetAsanInitIsRunning(u32 val) { asan_init_is_running = val; }
+void SetAsanInitIsRunning(u32 val) {
+#if SANITIZER_WINDOWS
+ atomic_store(&asan_init_is_running, val, memory_order_release);
+#else
+ asan_init_is_running = val;
+#endif
+}
-bool AsanInited() { return asan_inited == 1; }
+bool AsanInited() {
+#if SANITIZER_WINDOWS
+ return atomic_load(&asan_inited, memory_order_acquire) == 1;
+#else
+ return asan_inited == 1;
+#endif
+}
-bool AsanInitIsRunning() { return asan_init_is_running == 1; }
+bool AsanInitIsRunning() {
+#if SANITIZER_WINDOWS
+ return atomic_load(&asan_init_is_running, memory_order_acquire) == 1;
+#else
+ return asan_init_is_running == 1;
+#endif
+}
+
+void CheckAsanInitRunning() {
+#if SANITIZER_WINDOWS
+ while (AsanInitIsRunning()) {
+ // If ASAN is initializing on another thread, wait for it to finish.
+ }
+#endif
+ return;
+}
bool replace_intrin_cached;
@@ -391,6 +429,7 @@ void PrintAddressSpaceLayout() {
}
static void AsanInitInternal() {
+ CheckAsanInitRunning();
if (LIKELY(AsanInited()))
return;
SanitizerToolName = "AddressSanitizer";
diff --git a/compiler-rt/lib/asan/asan_thread.cpp b/compiler-rt/lib/asan/asan_thread.cpp
index 8798968947e82e6..88d526069352bcb 100644
--- a/compiler-rt/lib/asan/asan_thread.cpp
+++ b/compiler-rt/lib/asan/asan_thread.cpp
@@ -27,6 +27,10 @@ namespace __asan {
// AsanThreadContext implementation.
+#if SANITIZER_WINDOWS
+static atomic_uint8_t main_thread_created{0};
+#endif
+
void AsanThreadContext::OnCreated(void *arg) {
CreateThreadContextArgs *args = static_cast<CreateThreadContextArgs *>(arg);
if (args->stack)
@@ -93,6 +97,11 @@ AsanThreadContext *GetThreadContextByTidLocked(u32 tid) {
AsanThread *AsanThread::Create(const void *start_data, uptr data_size,
u32 parent_tid, StackTrace *stack,
bool detached) {
+#if SANITIZER_WINDOWS
+ while (atomic_load(&main_thread_created, memory_order_acquire) == 0) {
+ // If another thread is trying to be created before the main thread, wait.
+ }
+#endif
uptr PageSize = GetPageSizeCached();
uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
AsanThread *thread = (AsanThread *)MmapOrDie(size, __func__);
@@ -288,11 +297,25 @@ void AsanThread::ThreadStart(tid_t os_id) {
}
AsanThread *CreateMainThread() {
+// Depending on the loading thread, specifically in managed scenarios, the main
+// thread can be created after other threads on Windows. This ensures we start
+// the main thread before those threads.
+# if SANITIZER_WINDOWS
+ uptr PageSize = GetPageSizeCached();
+ uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
+ AsanThread *main_thread = (AsanThread *)MmapOrDie(size, __func__);
+ AsanThreadContext::CreateThreadContextArgs args = {main_thread, nullptr};
+ asanThreadRegistry().CreateThread(0, true, kMainTid, &args);
+ SetCurrentThread(main_thread);
+ main_thread->ThreadStart(internal_getpid());
+ atomic_store(&main_thread_created, 1, memory_order_release);
+# else
AsanThread *main_thread = AsanThread::Create(
/* parent_tid */ kMainTid,
/* stack */ nullptr, /* detached */ true);
SetCurrentThread(main_thread);
main_thread->ThreadStart(internal_getpid());
+# endif
return main_thread;
}
>From 683139e76cc9f31d7f9f43d804f8e788d3679b64 Mon Sep 17 00:00:00 2001
From: Zachary Johnson <zajohnson at microsoft.com>
Date: Thu, 16 Nov 2023 10:14:11 -0500
Subject: [PATCH 2/2] adding yields
---
compiler-rt/lib/asan/asan_rtl.cpp | 2 +-
compiler-rt/lib/asan/asan_thread.cpp | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/compiler-rt/lib/asan/asan_rtl.cpp b/compiler-rt/lib/asan/asan_rtl.cpp
index ade77d68f36d56d..092ddf15d5a3db2 100644
--- a/compiler-rt/lib/asan/asan_rtl.cpp
+++ b/compiler-rt/lib/asan/asan_rtl.cpp
@@ -115,9 +115,9 @@ void CheckAsanInitRunning() {
#if SANITIZER_WINDOWS
while (AsanInitIsRunning()) {
// If ASAN is initializing on another thread, wait for it to finish.
+ internal_sched_yield();
}
#endif
- return;
}
bool replace_intrin_cached;
diff --git a/compiler-rt/lib/asan/asan_thread.cpp b/compiler-rt/lib/asan/asan_thread.cpp
index 88d526069352bcb..dc0ad2caf3bbd10 100644
--- a/compiler-rt/lib/asan/asan_thread.cpp
+++ b/compiler-rt/lib/asan/asan_thread.cpp
@@ -100,6 +100,7 @@ AsanThread *AsanThread::Create(const void *start_data, uptr data_size,
#if SANITIZER_WINDOWS
while (atomic_load(&main_thread_created, memory_order_acquire) == 0) {
// If another thread is trying to be created before the main thread, wait.
+ internal_sched_yield();
}
#endif
uptr PageSize = GetPageSizeCached();
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