[compiler-rt] r372348 - [lsan] Fix deadlock in dl_iterate_phdr.
Evgeniy Stepanov via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 19 12:52:57 PDT 2019
Author: eugenis
Date: Thu Sep 19 12:52:57 2019
New Revision: 372348
URL: http://llvm.org/viewvc/llvm-project?rev=372348&view=rev
Log:
[lsan] Fix deadlock in dl_iterate_phdr.
Summary:
Do not grab the allocator lock before calling dl_iterate_phdr. This may
cause a lock order inversion with (valid) user code that uses malloc
inside a dl_iterate_phdr callback.
Reviewers: vitalybuka, hctim
Subscribers: jfb, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D67738
Added:
compiler-rt/trunk/test/lsan/TestCases/Linux/libdl_deadlock.cpp
Modified:
compiler-rt/trunk/lib/lsan/lsan_common.cpp
compiler-rt/trunk/lib/lsan/lsan_common.h
compiler-rt/trunk/lib/lsan/lsan_common_linux.cpp
compiler-rt/trunk/lib/lsan/lsan_common_mac.cpp
Modified: compiler-rt/trunk/lib/lsan/lsan_common.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/lsan/lsan_common.cpp?rev=372348&r1=372347&r2=372348&view=diff
==============================================================================
--- compiler-rt/trunk/lib/lsan/lsan_common.cpp (original)
+++ compiler-rt/trunk/lib/lsan/lsan_common.cpp Thu Sep 19 12:52:57 2019
@@ -570,11 +570,7 @@ static bool CheckForLeaks() {
EnsureMainThreadIDIsCorrect();
CheckForLeaksParam param;
param.success = false;
- LockThreadRegistry();
- LockAllocator();
- DoStopTheWorld(CheckForLeaksCallback, ¶m);
- UnlockAllocator();
- UnlockThreadRegistry();
+ LockStuffAndStopTheWorld(CheckForLeaksCallback, ¶m);
if (!param.success) {
Report("LeakSanitizer has encountered a fatal error.\n");
Modified: compiler-rt/trunk/lib/lsan/lsan_common.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/lsan/lsan_common.h?rev=372348&r1=372347&r2=372348&view=diff
==============================================================================
--- compiler-rt/trunk/lib/lsan/lsan_common.h (original)
+++ compiler-rt/trunk/lib/lsan/lsan_common.h Thu Sep 19 12:52:57 2019
@@ -129,8 +129,9 @@ struct RootRegion {
InternalMmapVector<RootRegion> const *GetRootRegions();
void ScanRootRegion(Frontier *frontier, RootRegion const ®ion,
uptr region_begin, uptr region_end, bool is_readable);
-// Run stoptheworld while holding any platform-specific locks.
-void DoStopTheWorld(StopTheWorldCallback callback, void* argument);
+// Run stoptheworld while holding any platform-specific locks, as well as the
+// allocator and thread registry locks.
+void LockStuffAndStopTheWorld(StopTheWorldCallback callback, void* argument);
void ScanRangeForPointers(uptr begin, uptr end,
Frontier *frontier,
Modified: compiler-rt/trunk/lib/lsan/lsan_common_linux.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/lsan/lsan_common_linux.cpp?rev=372348&r1=372347&r2=372348&view=diff
==============================================================================
--- compiler-rt/trunk/lib/lsan/lsan_common_linux.cpp (original)
+++ compiler-rt/trunk/lib/lsan/lsan_common_linux.cpp Thu Sep 19 12:52:57 2019
@@ -115,10 +115,14 @@ void HandleLeaks() {
if (common_flags()->exitcode) Die();
}
-static int DoStopTheWorldCallback(struct dl_phdr_info *info, size_t size,
- void *data) {
+static int LockStuffAndStopTheWorldCallback(struct dl_phdr_info *info,
+ size_t size, void *data) {
+ LockThreadRegistry();
+ LockAllocator();
DoStopTheWorldParam *param = reinterpret_cast<DoStopTheWorldParam *>(data);
StopTheWorld(param->callback, param->argument);
+ UnlockAllocator();
+ UnlockThreadRegistry();
return 1;
}
@@ -130,9 +134,9 @@ static int DoStopTheWorldCallback(struct
// while holding the libdl lock in the parent thread, we can safely reenter it
// in the tracer. The solution is to run stoptheworld from a dl_iterate_phdr()
// callback in the parent thread.
-void DoStopTheWorld(StopTheWorldCallback callback, void *argument) {
+void LockStuffAndStopTheWorld(StopTheWorldCallback callback, void *argument) {
DoStopTheWorldParam param = {callback, argument};
- dl_iterate_phdr(DoStopTheWorldCallback, ¶m);
+ dl_iterate_phdr(LockStuffAndStopTheWorldCallback, ¶m);
}
} // namespace __lsan
Modified: compiler-rt/trunk/lib/lsan/lsan_common_mac.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/lsan/lsan_common_mac.cpp?rev=372348&r1=372347&r2=372348&view=diff
==============================================================================
--- compiler-rt/trunk/lib/lsan/lsan_common_mac.cpp (original)
+++ compiler-rt/trunk/lib/lsan/lsan_common_mac.cpp Thu Sep 19 12:52:57 2019
@@ -193,8 +193,12 @@ void ProcessPlatformSpecificAllocations(
// causes rare race conditions.
void HandleLeaks() {}
-void DoStopTheWorld(StopTheWorldCallback callback, void *argument) {
+void LockStuffAndStopTheWorld(StopTheWorldCallback callback, void *argument) {
+ LockThreadRegistry();
+ LockAllocator();
StopTheWorld(callback, argument);
+ UnlockAllocator();
+ UnlockThreadRegistry();
}
} // namespace __lsan
Added: compiler-rt/trunk/test/lsan/TestCases/Linux/libdl_deadlock.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/lsan/TestCases/Linux/libdl_deadlock.cpp?rev=372348&view=auto
==============================================================================
--- compiler-rt/trunk/test/lsan/TestCases/Linux/libdl_deadlock.cpp (added)
+++ compiler-rt/trunk/test/lsan/TestCases/Linux/libdl_deadlock.cpp Thu Sep 19 12:52:57 2019
@@ -0,0 +1,52 @@
+// Regression test for a deadlock in leak detection,
+// where lsan would call dl_iterate_phdr while holding the allocator lock.
+// RUN: %clangxx_lsan %s -o %t && %run %t
+
+#include <link.h>
+#include <mutex>
+#include <stdlib.h>
+#include <thread>
+#include <unistd.h>
+
+std::mutex in, out;
+
+int Callback(struct dl_phdr_info *info, size_t size, void *data) {
+ for (int step = 0; step < 50; ++step) {
+ void *p[1000];
+ for (int i = 0; i < 1000; ++i)
+ p[i] = malloc(10 * i);
+
+ if (step == 0)
+ in.unlock();
+
+ for (int i = 0; i < 1000; ++i)
+ free(p[i]);
+ }
+ out.unlock();
+ return 1; // just once
+}
+
+void Watchdog() {
+ // This is just a fail-safe to turn a deadlock (in case the bug reappears)
+ // into a (slow) test failure.
+ usleep(10000000);
+ if (!out.try_lock()) {
+ write(2, "DEADLOCK\n", 9);
+ exit(1);
+ }
+}
+
+int main() {
+ in.lock();
+ out.lock();
+
+ std::thread t([] { dl_iterate_phdr(Callback, nullptr); });
+ t.detach();
+
+ std::thread w(Watchdog);
+ w.detach();
+
+ // Wait for the malloc thread to preheat, then start leak detection (on exit)
+ in.lock();
+ return 0;
+}
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