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//===- FuzzerFork.cpp - run fuzzing in separate subprocesses --------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// Spawn and orchestrate separate fuzzing processes.
//===----------------------------------------------------------------------===//
#include "FuzzerCommand.h"
#include "FuzzerFork.h"
#include "FuzzerIO.h"
#include "FuzzerMerge.h"
#include "FuzzerSHA1.h"
#include "FuzzerUtil.h"
#include <mutex>
#include <thread>
#include <queue>
namespace fuzzer {
struct FuzzJob {
// Inputs.
Command Cmd;
std::string CorpusDir;
std::string LogPath;
std::string CFPath;
// Fuzzing Outputs.
int ExitCode;
};
struct GlobalEnv {
Vector<std::string> Args;
Vector<std::string> CorpusDirs;
std::string MainCorpusDir;
std::string TempDir;
Set<uint32_t> Features;
Vector<std::string> Files;
Random *Rand;
int Verbosity = 0;
FuzzJob *CreateNewJob(size_t JobId) {
Command Cmd(Args);
Cmd.removeFlag("fork");
for (auto &C : CorpusDirs) // Remove all corpora from the args.
Cmd.removeArgument(C);
Cmd.addFlag("reload", "0"); // working in an isolated dir, no reload.
Cmd.addFlag("max_total_time", std::to_string(std::min((size_t)300, JobId)));
auto Job = new FuzzJob;
std::string Seeds;
if (size_t CorpusSubsetSize = std::min(Files.size(), (size_t)100))
for (size_t i = 0; i < CorpusSubsetSize; i++)
Seeds += (Seeds.empty() ? "" : ",") +
Files[Rand->SkewTowardsLast(Files.size())];
if (!Seeds.empty())
Cmd.addFlag("seed_inputs", Seeds);
Job->LogPath = DirPlusFile(TempDir, std::to_string(JobId) + ".log");
Job->CorpusDir = DirPlusFile(TempDir, "C" + std::to_string(JobId));
Job->CFPath = DirPlusFile(TempDir, std::to_string(JobId) + ".merge");
Cmd.addArgument(Job->CorpusDir);
RmDirRecursive(Job->CorpusDir);
MkDir(Job->CorpusDir);
Cmd.setOutputFile(Job->LogPath);
Cmd.combineOutAndErr();
Job->Cmd = Cmd;
if (Verbosity >= 2)
Printf("Job %zd/%p Created: %s\n", JobId, Job,
Job->Cmd.toString().c_str());
// Start from very short runs and gradually increase them.
return Job;
}
void RunOneMergeJob(FuzzJob *Job) {
Vector<SizedFile> TempFiles;
GetSizedFilesFromDir(Job->CorpusDir, &TempFiles);
Vector<std::string> FilesToAdd;
Set<uint32_t> NewFeatures;
CrashResistantMerge(Args, {}, TempFiles, &FilesToAdd, Features,
&NewFeatures, Job->CFPath, false);
RemoveFile(Job->CFPath);
for (auto &Path : FilesToAdd) {
auto U = FileToVector(Path);
auto NewPath = DirPlusFile(MainCorpusDir, Hash(U));
WriteToFile(U, NewPath);
Files.push_back(NewPath);
}
Printf("Removing %s\n", Job->CorpusDir.c_str());
RmDirRecursive(Job->CorpusDir);
Features.insert(NewFeatures.begin(), NewFeatures.end());
Printf("INFO: temp_files: %zd files_added: %zd newft: %zd ft: %zd\n",
TempFiles.size(), FilesToAdd.size(), NewFeatures.size(),
Features.size());
}
};
struct JobQueue {
std::queue<FuzzJob *> Qu;
std::mutex Mu;
void Push(FuzzJob *Job) {
std::lock_guard<std::mutex> Lock(Mu);
Qu.push(Job);
}
FuzzJob *Pop() {
std::lock_guard<std::mutex> Lock(Mu);
if (Qu.empty()) return nullptr;
auto Job = Qu.front();
Qu.pop();
return Job;
}
};
void WorkerThread(std::atomic<bool> *Stop, JobQueue *FuzzQ, JobQueue *MergeQ) {
while (!*Stop) {
auto Job = FuzzQ->Pop();
// Printf("WorkerThread: job %p\n", Job);
if (!Job) {
SleepSeconds(1);
continue;
}
Job->ExitCode = ExecuteCommand(Job->Cmd);
MergeQ->Push(Job);
}
}
// This is just a skeleton of an experimental -fork=1 feature.
void FuzzWithFork(Random &Rand, const FuzzingOptions &Options,
const Vector<std::string> &Args,
const Vector<std::string> &CorpusDirs, int NumJobs) {
Printf("INFO: -fork=%d: doing fuzzing in a separate process in order to "
"be more resistant to crashes, timeouts, and OOMs\n", NumJobs);
GlobalEnv Env;
Env.Args = Args;
Env.CorpusDirs = CorpusDirs;
Env.Rand = &Rand;
Env.Verbosity = Options.Verbosity;
Vector<SizedFile> SeedFiles;
for (auto &Dir : CorpusDirs)
GetSizedFilesFromDir(Dir, &SeedFiles);
std::sort(SeedFiles.begin(), SeedFiles.end());
Env.TempDir = TempPath(".dir");
RmDirRecursive(Env.TempDir); // in case there is a leftover from old runs.
MkDir(Env.TempDir);
if (CorpusDirs.empty())
MkDir(Env.MainCorpusDir = DirPlusFile(Env.TempDir, "C"));
else
Env.MainCorpusDir = CorpusDirs[0];
auto CFPath = DirPlusFile(Env.TempDir, "merge.txt");
CrashResistantMerge(Env.Args, {}, SeedFiles, &Env.Files, {}, &Env.Features,
CFPath, false);
RemoveFile(CFPath);
Printf("INFO: -fork=%d: %zd seeds, starting to fuzz; scratch: %s\n",
NumJobs, Env.Files.size(), Env.TempDir.c_str());
int ExitCode = 0;
JobQueue FuzzQ, MergeQ;
std::atomic<bool> Stop(false);
size_t JobId = 1;
Vector<std::thread> Threads;
for (int t = 0; t < NumJobs; t++) {
Threads.push_back(std::thread(WorkerThread, &Stop, &FuzzQ, &MergeQ));
FuzzQ.Push(Env.CreateNewJob(JobId++));
}
while (!Stop) {
auto Job = MergeQ.Pop();
if (!Job) {
SleepSeconds(1);
continue;
}
ExitCode = Job->ExitCode;
if (ExitCode != Options.InterruptExitCode)
Env.RunOneMergeJob(Job);
// Continue if our crash is one of the ignorred ones.
if (Options.IgnoreTimeouts && ExitCode == Options.TimeoutExitCode)
;
else if (Options.IgnoreOOMs && ExitCode == Options.OOMExitCode)
;
else if (ExitCode == Options.InterruptExitCode)
Stop = true;
else if (ExitCode != 0) {
// And exit if we don't ignore this crash.
Printf("INFO: log from the inner process:\n%s",
FileToString(Job->LogPath).c_str());
Stop = true;
}
RemoveFile(Job->LogPath);
delete Job;
FuzzQ.Push(Env.CreateNewJob(JobId++));
}
Stop = true;
for (auto &T : Threads)
T.join();
RmDirRecursive(Env.TempDir);
// Use the exit code from the last child process.
Printf("Fork: exiting: %d\n", ExitCode);
exit(ExitCode);
}
} // namespace fuzzer
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