Libfuzzer fix for Ctrl + c not working with -fork and -ignore_crashes=1

[SyrasX]

Summary

In some cases running Libfuzzer in fork mode with -ignore_crashes=1 counts ctrl+c as crash and restarts.

Thread: https://github.com/google/oss-fuzz/issues/4547

Credit: Marcel Boehme <[e-mail]>

[vitalybuka]

compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp

30

why this does not use Options->InterruptExitCode?

[SyrasX]

FuzzingOptions->InterruptExitCode

[SyrasX]

compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp

30

Yeah just inattention sorry.

[SyrasX]

Is there anything I need to do after the diff got accepted ? Don't think I have a way to commit. @vitalybuka

[vitalybuka]

I can land it for you, but can't figure out email to attach to the commit.

[SyrasX]

In D130990#3724005, @vitalybuka wrote:

I can land it for you, but can't figure out email to attach to the commit.

Thanks, should be [e-mail]

[vitalybuka]

update

compiler-rt/lib/fuzzer/FuzzerInternal.h

public:
 
   bool InFuzzingThread() const { return IsMyThread; }
   size_t GetCurrentUnitInFuzzingThead(const uint8_t **Data) const;
   void TryDetectingAMemoryLeak(const uint8_t *Data, size_t Size,
                                bool DuringInitialCorpusExecution);
 
   void HandleMalloc(size_t Size);
   static void MaybeExitGracefully();
+  static int InterruptExitCode();
   std::string WriteToOutputCorpus(const Unit &U);
 
 private:
   void AlarmCallback();
   void CrashCallback();
   void ExitCallback();
   void CrashOnOverwrittenData();
   void InterruptCallback();

compiler-rt/lib/fuzzer/FuzzerLoop.cpp

 void Fuzzer::MaybeExitGracefully() {
   if (!F->GracefulExitRequested) return;
   Printf("==%lu== INFO: libFuzzer: exiting as requested\n", GetPid());
   RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
   F->PrintFinalStats();
   _Exit(0);
 }
 
+int Fuzzer::InterruptExitCode() {
+  assert(F);
+  return F->Options.InterruptExitCode;
+}
+
 void Fuzzer::InterruptCallback() {
   Printf("==%lu== libFuzzer: run interrupted; exiting\n", GetPid());
   PrintFinalStats();
   ScopedDisableMsanInterceptorChecks S; // RmDirRecursive may call opendir().
   RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
   // Stop right now, don't perform any at-exit actions.
   _Exit(Options.InterruptExitCode);
 }

compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp

 //===- FuzzerUtilLinux.cpp - Misc utils for Linux. ------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 // Misc utils for Linux.
 //===----------------------------------------------------------------------===//
 #include "FuzzerPlatform.h"
 #if LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FREEBSD ||                \
     LIBFUZZER_EMSCRIPTEN
 #include "FuzzerCommand.h"
+#include "FuzzerInternal.h"
 
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
 
 namespace fuzzer {
 
 int ExecuteCommand(const Command &Cmd) {
   std::string CmdLine = Cmd.toString();
   int exit_code = system(CmdLine.c_str());
   if (WIFEXITED(exit_code))
     return WEXITSTATUS(exit_code);
+  if (WIFSIGNALED(exit_code) && WTERMSIG(exit_code) == SIGINT)
+    return Fuzzer::InterruptExitCode();
   return exit_code;
 }
 
 void DiscardOutput(int Fd) {
   FILE* Temp = fopen("/dev/null", "w");
   if (!Temp)
     return;
   dup2(fileno(Temp), Fd);
   fclose(Temp);
 }
 
 } // namespace fuzzer
 
 #endif