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llvm-project/compiler-rt/lib/fuzzer/FuzzerFork.cpp

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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 "FuzzerInternal.h"
#include "FuzzerMerge.h"
#include "FuzzerSHA1.h"
#include "FuzzerTracePC.h"
#include "FuzzerUtil.h"
#include <atomic>
#include <chrono>
#include <fstream>
#include <memory>
#include <mutex>
#include <queue>
#include <sstream>
#include <thread>
namespace fuzzer {
struct Stats {
size_t number_of_executed_units = 0;
size_t peak_rss_mb = 0;
size_t average_exec_per_sec = 0;
};
static Stats ParseFinalStatsFromLog(const std::string &LogPath) {
std::ifstream In(LogPath);
std::string Line;
Stats Res;
struct {
const char *Name;
size_t *Var;
} NameVarPairs[] = {
{"stat::number_of_executed_units:", &Res.number_of_executed_units},
{"stat::peak_rss_mb:", &Res.peak_rss_mb},
{"stat::average_exec_per_sec:", &Res.average_exec_per_sec},
{nullptr, nullptr},
};
while (std::getline(In, Line, '\n')) {
if (Line.find("stat::") != 0) continue;
std::istringstream ISS(Line);
std::string Name;
size_t Val;
ISS >> Name >> Val;
for (size_t i = 0; NameVarPairs[i].Name; i++)
if (Name == NameVarPairs[i].Name)
*NameVarPairs[i].Var = Val;
}
return Res;
}
struct FuzzJob {
// Inputs.
Command Cmd;
std::string CorpusDir;
std::string FeaturesDir;
std::string LogPath;
std::string SeedListPath;
std::string CFPath;
// Fuzzing Outputs.
int ExitCode;
~FuzzJob() {
RemoveFile(CFPath);
RemoveFile(LogPath);
RemoveFile(SeedListPath);
RmDirRecursive(CorpusDir);
RmDirRecursive(FeaturesDir);
}
};
struct GlobalEnv {
Vector<std::string> Args;
Vector<std::string> CorpusDirs;
std::string MainCorpusDir;
std::string TempDir;
Set<uint32_t> Features, Cov;
Vector<std::string> Files;
Random *Rand;
std::chrono::system_clock::time_point ProcessStartTime;
int Verbosity = 0;
size_t NumTimeouts = 0;
size_t NumOOMs = 0;
size_t NumCrashes = 0;
size_t NumRuns = 0;
size_t secondsSinceProcessStartUp() const {
return std::chrono::duration_cast<std::chrono::seconds>(
std::chrono::system_clock::now() - ProcessStartTime)
.count();
}
FuzzJob *CreateNewJob(size_t JobId) {
Command Cmd(Args);
Cmd.removeFlag("fork");
Cmd.removeFlag("runs");
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("print_final_stats", "1");
Cmd.addFlag("print_funcs", "0"); // no need to spend time symbolizing.
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)sqrt(Files.size() + 2)))
for (size_t i = 0; i < CorpusSubsetSize; i++)
Seeds += (Seeds.empty() ? "" : ",") +
Files[Rand->SkewTowardsLast(Files.size())];
if (!Seeds.empty()) {
Job->SeedListPath = std::to_string(JobId) + ".seeds";
WriteToFile(Seeds, Job->SeedListPath);
Cmd.addFlag("seed_inputs", "@" + Job->SeedListPath);
}
Job->LogPath = DirPlusFile(TempDir, std::to_string(JobId) + ".log");
Job->CorpusDir = DirPlusFile(TempDir, "C" + std::to_string(JobId));
Job->FeaturesDir = DirPlusFile(TempDir, "F" + std::to_string(JobId));
Job->CFPath = DirPlusFile(TempDir, std::to_string(JobId) + ".merge");
Cmd.addArgument(Job->CorpusDir);
Cmd.addFlag("features_dir", Job->FeaturesDir);
for (auto &D : {Job->CorpusDir, Job->FeaturesDir}) {
RmDirRecursive(D);
MkDir(D);
}
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) {
auto Stats = ParseFinalStatsFromLog(Job->LogPath);
NumRuns += Stats.number_of_executed_units;
Vector<SizedFile> TempFiles, MergeCandidates;
// Read all newly created inputs and their feature sets.
// Choose only those inputs that have new features.
GetSizedFilesFromDir(Job->CorpusDir, &TempFiles);
std::sort(TempFiles.begin(), TempFiles.end());
for (auto &F : TempFiles) {
auto FeatureFile = F.File;
FeatureFile.replace(0, Job->CorpusDir.size(), Job->FeaturesDir);
auto FeatureBytes = FileToVector(FeatureFile, 0, false);
assert((FeatureBytes.size() % sizeof(uint32_t)) == 0);
Vector<uint32_t> NewFeatures(FeatureBytes.size() / sizeof(uint32_t));
memcpy(NewFeatures.data(), FeatureBytes.data(), FeatureBytes.size());
for (auto Ft : NewFeatures) {
if (!Features.count(Ft)) {
MergeCandidates.push_back(F);
break;
}
}
}
if (MergeCandidates.empty()) return;
Vector<std::string> FilesToAdd;
Set<uint32_t> NewFeatures, NewCov;
CrashResistantMerge(Args, {}, MergeCandidates, &FilesToAdd, Features,
&NewFeatures, Cov, &NewCov, Job->CFPath, false);
for (auto &Path : FilesToAdd) {
auto U = FileToVector(Path);
auto NewPath = DirPlusFile(MainCorpusDir, Hash(U));
WriteToFile(U, NewPath);
Files.push_back(NewPath);
}
Features.insert(NewFeatures.begin(), NewFeatures.end());
Cov.insert(NewCov.begin(), NewCov.end());
for (auto Idx : NewCov)
if (auto *TE = TPC.PCTableEntryByIdx(Idx))
if (TPC.PcIsFuncEntry(TE))
PrintPC(" NEW_FUNC: %p %F %L\n", "",
TPC.GetNextInstructionPc(TE->PC));
if (!FilesToAdd.empty() || Job->ExitCode != 0)
Printf("#%zd: cov: %zd ft: %zd corp: %zd exec/s %zd "
"oom/timeout/crash: %zd/%zd/%zd time: %zds\n", NumRuns,
Cov.size(), Features.size(), Files.size(),
Stats.average_exec_per_sec,
NumOOMs, NumTimeouts, NumCrashes, secondsSinceProcessStartUp());
}
};
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->load()) {
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: fuzzing in separate process(s)\n", NumJobs);
GlobalEnv Env;
Env.Args = Args;
Env.CorpusDirs = CorpusDirs;
Env.Rand = &Rand;
Env.Verbosity = Options.Verbosity;
Env.ProcessStartTime = std::chrono::system_clock::now();
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,
{}, &Env.Cov,
CFPath, false);
RemoveFile(CFPath);
Printf("INFO: -fork=%d: %zd seed inputs, starting to fuzz in %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 (true) {
std::unique_ptr<FuzzJob> Job(MergeQ.Pop());
if (!Job) {
if (Stop)
break;
SleepSeconds(1);
continue;
}
ExitCode = Job->ExitCode;
if (ExitCode == Options.InterruptExitCode) {
Printf("==%lu== libFuzzer: a child was interrupted; exiting\n", GetPid());
Stop = true;
break;
}
Fuzzer::MaybeExitGracefully();
Env.RunOneMergeJob(Job.get());
// Continue if our crash is one of the ignorred ones.
if (Options.IgnoreTimeouts && ExitCode == Options.TimeoutExitCode)
Env.NumTimeouts++;
else if (Options.IgnoreOOMs && ExitCode == Options.OOMExitCode)
Env.NumOOMs++;
else if (ExitCode != 0) {
Env.NumCrashes++;
if (Options.IgnoreCrashes) {
std::ifstream In(Job->LogPath);
std::string Line;
while (std::getline(In, Line, '\n'))
if (Line.find("ERROR:") != Line.npos ||
Line.find("runtime error:") != Line.npos)
Printf("%s\n", Line.c_str());
} else {
// 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;
}
}
// Stop if we are over the time budget.
// This is not precise, since other threads are still running
// and we will wait while joining them.
// We also don't stop instantly: other jobs need to finish.
if (Options.MaxTotalTimeSec > 0 && !Stop &&
Env.secondsSinceProcessStartUp() >= (size_t)Options.MaxTotalTimeSec) {
Printf("INFO: fuzzed for %zd seconds, wrapping up soon\n",
Env.secondsSinceProcessStartUp());
Stop = true;
}
if (!Stop && Env.NumRuns >= Options.MaxNumberOfRuns) {
Printf("INFO: fuzzed for %zd iterations, wrapping up soon\n",
Env.NumRuns);
Stop = true;
}
if (!Stop)
FuzzQ.Push(Env.CreateNewJob(JobId++));
}
Stop = true;
for (auto &T : Threads)
T.join();
// The workers have terminated. Don't try to remove the directory before they
// terminate to avoid a race condition preventing cleanup on Windows.
RmDirRecursive(Env.TempDir);
// Use the exit code from the last child process.
Printf("INFO: exiting: %d time: %zds\n", ExitCode,
Env.secondsSinceProcessStartUp());
exit(ExitCode);
}
} // namespace fuzzer
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