[libFuzzer] Guard symbolization with try-lock.
Summary:
When out-of-memory or timeout occurs, threads can be stopped during
symbolization, thereby causing a deadlock when the OOM/TO handlers
attempt symbolization. We avoid this deadlock by skipping symbolization
if another thread is symbolizing.
Reviewers: kcc
Reviewed By: kcc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D46605
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@331825 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerUtil.cpp b/FuzzerUtil.cpp
index 96b37d3..6286f9a 100644
--- a/FuzzerUtil.cpp
+++ b/FuzzerUtil.cpp
@@ -16,6 +16,7 @@
#include <chrono>
#include <cstring>
#include <errno.h>
+#include <mutex>
#include <signal.h>
#include <sstream>
#include <stdio.h>
@@ -179,8 +180,12 @@
return Res;
}
+static std::mutex SymbolizeMutex;
+
std::string DescribePC(const char *SymbolizedFMT, uintptr_t PC) {
- if (!EF->__sanitizer_symbolize_pc) return "<can not symbolize>";
+ std::unique_lock<std::mutex> l(SymbolizeMutex, std::try_to_lock);
+ if (!EF->__sanitizer_symbolize_pc || !l.owns_lock())
+ return "<can not symbolize>";
char PcDescr[1024] = {};
EF->__sanitizer_symbolize_pc(reinterpret_cast<void*>(PC),
SymbolizedFMT, PcDescr, sizeof(PcDescr));
@@ -195,6 +200,18 @@
Printf(FallbackFMT, PC);
}
+void PrintStackTrace() {
+ std::unique_lock<std::mutex> l(SymbolizeMutex, std::try_to_lock);
+ if (EF->__sanitizer_print_stack_trace && l.owns_lock())
+ EF->__sanitizer_print_stack_trace();
+}
+
+void PrintMemoryProfile() {
+ std::unique_lock<std::mutex> l(SymbolizeMutex, std::try_to_lock);
+ if (EF->__sanitizer_print_memory_profile && l.owns_lock())
+ EF->__sanitizer_print_memory_profile(95, 8);
+}
+
unsigned NumberOfCpuCores() {
unsigned N = std::thread::hardware_concurrency();
if (!N) {