[compiler-rt] r359254 - [libFuzzer] Disable MSan interceptors in SIGINT handler.

[Matt Morehouse via llvm-commits]

Author: morehouse
Date: Thu Apr 25 17:17:41 2019
New Revision: 359254

URL: http://llvm.org/viewvc/llvm-project?rev=359254&view=rev
Log:
[libFuzzer] Disable MSan interceptors in SIGINT handler.

Summary:
Avoids an MSan false positive if the SIGINT comes while the user
callback is running.  The false positive happens when the interrupt
handler calls opendir() to remove some temporary files, which is
intercepted by MSan.

Fixes https://github.com/google/oss-fuzz/issues/2332.

Reviewers: kcc

Reviewed By: kcc

Subscribers: llvm-commits, Dor1s, metzman

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61163

Added:
    compiler-rt/trunk/test/fuzzer/sigint.test
Modified:
    compiler-rt/trunk/lib/fuzzer/FuzzerLoop.cpp

Modified: compiler-rt/trunk/lib/fuzzer/FuzzerLoop.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/fuzzer/FuzzerLoop.cpp?rev=359254&r1=359253&r2=359254&view=diff
==============================================================================
--- compiler-rt/trunk/lib/fuzzer/FuzzerLoop.cpp (original)
+++ compiler-rt/trunk/lib/fuzzer/FuzzerLoop.cpp Thu Apr 25 17:17:41 2019
@@ -266,6 +266,7 @@ void Fuzzer::MaybeExitGracefully() {
 void Fuzzer::InterruptCallback() {
   Printf("==%lu== libFuzzer: run interrupted; exiting\n", GetPid());
   PrintFinalStats();
+  ScopedDisableMsanInterceptorChecks S; // RmDirRecursive may call opendir().
   RmDirRecursive(TempPath(".dir"));
   // Stop right now, don't perform any at-exit actions.
   _Exit(Options.InterruptExitCode);
@@ -681,7 +682,7 @@ void Fuzzer::MutateAndTestOne() {
         Size <= CurrentMaxMutationLen)
       NewSize = MD.MutateWithMask(CurrentUnitData, Size, Size,
                                   II.DataFlowTraceForFocusFunction);
-    
+
     // If MutateWithMask either failed or wasn't called, call default Mutate.
     if (!NewSize)
       NewSize = MD.Mutate(CurrentUnitData, Size, CurrentMaxMutationLen);

Added: compiler-rt/trunk/test/fuzzer/sigint.test
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/fuzzer/sigint.test?rev=359254&view=auto
==============================================================================
--- compiler-rt/trunk/test/fuzzer/sigint.test (added)
+++ compiler-rt/trunk/test/fuzzer/sigint.test Thu Apr 25 17:17:41 2019
@@ -0,0 +1,17 @@
+# FIXME: Disabled on Windows for now because of reliance on posix only features
+# (eg: export, "&", pkill).
+UNSUPPORTED: darwin, windows
+
+# Check that libFuzzer exits gracefully under SIGINT with MSan.
+RUN: rm -rf %t
+RUN: mkdir -p %t
+RUN: %msan_compiler %S/SleepOneSecondTest.cpp -o %t/LFSIGINT
+
+RUN: %run %t/LFSIGINT 2> %t/log & export PID=$!
+RUN: sleep 2
+RUN: kill -SIGINT $PID
+RUN: sleep 3
+RUN: cat %t/log | FileCheck %s
+
+CHECK: libFuzzer: run interrupted; exiting
+CHECK-NOT: WARNING: MemorySanitizer