1 //===- FuzzerLoop.cpp - Fuzzer's main loop --------------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 //===----------------------------------------------------------------------===//
11 #include "FuzzerCorpus.h"
13 #include "FuzzerInternal.h"
14 #include "FuzzerMutate.h"
15 #include "FuzzerPlatform.h"
16 #include "FuzzerRandom.h"
17 #include "FuzzerTracePC.h"
24 #if defined(__has_include)
25 #if __has_include(<sanitizer / lsan_interface.h>)
26 #include <sanitizer/lsan_interface.h>
30 #define NO_SANITIZE_MEMORY
31 #if defined(__has_feature)
32 #if __has_feature(memory_sanitizer)
33 #undef NO_SANITIZE_MEMORY
34 #define NO_SANITIZE_MEMORY __attribute__((no_sanitize_memory))
39 static const size_t kMaxUnitSizeToPrint = 256;
41 thread_local bool Fuzzer::IsMyThread;
43 bool RunningUserCallback = false;
45 // Only one Fuzzer per process.
48 // Leak detection is expensive, so we first check if there were more mallocs
49 // than frees (using the sanitizer malloc hooks) and only then try to call lsan.
50 struct MallocFreeTracer {
51 void Start(int TraceLevel) {
52 this->TraceLevel = TraceLevel;
54 Printf("MallocFreeTracer: START\n");
58 // Returns true if there were more mallocs than frees.
61 Printf("MallocFreeTracer: STOP %zd %zd (%s)\n", Mallocs.load(),
62 Frees.load(), Mallocs == Frees ? "same" : "DIFFERENT");
63 bool Result = Mallocs > Frees;
69 std::atomic<size_t> Mallocs;
70 std::atomic<size_t> Frees;
73 std::recursive_mutex TraceMutex;
74 bool TraceDisabled = false;
77 static MallocFreeTracer AllocTracer;
79 // Locks printing and avoids nested hooks triggered from mallocs/frees in
83 TraceLock() : Lock(AllocTracer.TraceMutex) {
84 AllocTracer.TraceDisabled = !AllocTracer.TraceDisabled;
86 ~TraceLock() { AllocTracer.TraceDisabled = !AllocTracer.TraceDisabled; }
88 bool IsDisabled() const {
89 // This is already inverted value.
90 return !AllocTracer.TraceDisabled;
94 std::lock_guard<std::recursive_mutex> Lock;
97 ATTRIBUTE_NO_SANITIZE_MEMORY
98 void MallocHook(const volatile void *ptr, size_t size) {
99 size_t N = AllocTracer.Mallocs++;
100 F->HandleMalloc(size);
101 if (int TraceLevel = AllocTracer.TraceLevel) {
103 if (Lock.IsDisabled())
105 Printf("MALLOC[%zd] %p %zd\n", N, ptr, size);
106 if (TraceLevel >= 2 && EF)
111 ATTRIBUTE_NO_SANITIZE_MEMORY
112 void FreeHook(const volatile void *ptr) {
113 size_t N = AllocTracer.Frees++;
114 if (int TraceLevel = AllocTracer.TraceLevel) {
116 if (Lock.IsDisabled())
118 Printf("FREE[%zd] %p\n", N, ptr);
119 if (TraceLevel >= 2 && EF)
124 // Crash on a single malloc that exceeds the rss limit.
125 void Fuzzer::HandleMalloc(size_t Size) {
126 if (!Options.MallocLimitMb || (Size >> 20) < (size_t)Options.MallocLimitMb)
128 Printf("==%d== ERROR: libFuzzer: out-of-memory (malloc(%zd))\n", GetPid(),
130 Printf(" To change the out-of-memory limit use -rss_limit_mb=<N>\n\n");
132 DumpCurrentUnit("oom-");
133 Printf("SUMMARY: libFuzzer: out-of-memory\n");
135 _Exit(Options.OOMExitCode); // Stop right now.
138 Fuzzer::Fuzzer(UserCallback CB, InputCorpus &Corpus, MutationDispatcher &MD,
139 FuzzingOptions Options)
140 : CB(CB), Corpus(Corpus), MD(MD), Options(Options) {
141 if (EF->__sanitizer_set_death_callback)
142 EF->__sanitizer_set_death_callback(StaticDeathCallback);
147 if (Options.DetectLeaks && EF->__sanitizer_install_malloc_and_free_hooks)
148 EF->__sanitizer_install_malloc_and_free_hooks(MallocHook, FreeHook);
149 TPC.SetUseCounters(Options.UseCounters);
150 TPC.SetUseValueProfileMask(Options.UseValueProfile);
152 if (Options.Verbosity)
153 TPC.PrintModuleInfo();
154 if (!Options.OutputCorpus.empty() && Options.ReloadIntervalSec)
155 EpochOfLastReadOfOutputCorpus = GetEpoch(Options.OutputCorpus);
156 MaxInputLen = MaxMutationLen = Options.MaxLen;
157 TmpMaxMutationLen = 0; // Will be set once we load the corpus.
158 AllocateCurrentUnitData();
160 memset(BaseSha1, 0, sizeof(BaseSha1));
165 void Fuzzer::AllocateCurrentUnitData() {
166 if (CurrentUnitData || MaxInputLen == 0)
168 CurrentUnitData = new uint8_t[MaxInputLen];
171 void Fuzzer::StaticDeathCallback() {
176 void Fuzzer::DumpCurrentUnit(const char *Prefix) {
177 if (!CurrentUnitData)
178 return; // Happens when running individual inputs.
179 ScopedDisableMsanInterceptorChecks S;
180 MD.PrintMutationSequence();
181 Printf("; base unit: %s\n", Sha1ToString(BaseSha1).c_str());
182 size_t UnitSize = CurrentUnitSize;
183 if (UnitSize <= kMaxUnitSizeToPrint) {
184 PrintHexArray(CurrentUnitData, UnitSize, "\n");
185 PrintASCII(CurrentUnitData, UnitSize, "\n");
187 WriteUnitToFileWithPrefix({CurrentUnitData, CurrentUnitData + UnitSize},
192 void Fuzzer::DeathCallback() {
193 DumpCurrentUnit("crash-");
197 void Fuzzer::StaticAlarmCallback() {
202 void Fuzzer::StaticCrashSignalCallback() {
207 void Fuzzer::StaticExitCallback() {
212 void Fuzzer::StaticInterruptCallback() {
214 F->InterruptCallback();
217 void Fuzzer::StaticGracefulExitCallback() {
219 F->GracefulExitRequested = true;
220 Printf("INFO: signal received, trying to exit gracefully\n");
223 void Fuzzer::StaticFileSizeExceedCallback() {
224 Printf("==%lu== ERROR: libFuzzer: file size exceeded\n", GetPid());
228 void Fuzzer::CrashCallback() {
229 if (EF->__sanitizer_acquire_crash_state &&
230 !EF->__sanitizer_acquire_crash_state())
232 Printf("==%lu== ERROR: libFuzzer: deadly signal\n", GetPid());
234 Printf("NOTE: libFuzzer has rudimentary signal handlers.\n"
235 " Combine libFuzzer with AddressSanitizer or similar for better "
237 Printf("SUMMARY: libFuzzer: deadly signal\n");
238 DumpCurrentUnit("crash-");
240 _Exit(Options.ErrorExitCode); // Stop right now.
243 void Fuzzer::ExitCallback() {
244 if (!RunningUserCallback)
245 return; // This exit did not come from the user callback
246 if (EF->__sanitizer_acquire_crash_state &&
247 !EF->__sanitizer_acquire_crash_state())
249 Printf("==%lu== ERROR: libFuzzer: fuzz target exited\n", GetPid());
251 Printf("SUMMARY: libFuzzer: fuzz target exited\n");
252 DumpCurrentUnit("crash-");
254 _Exit(Options.ErrorExitCode);
257 void Fuzzer::MaybeExitGracefully() {
258 if (!F->GracefulExitRequested) return;
259 Printf("==%lu== INFO: libFuzzer: exiting as requested\n", GetPid());
260 RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
261 F->PrintFinalStats();
265 void Fuzzer::InterruptCallback() {
266 Printf("==%lu== libFuzzer: run interrupted; exiting\n", GetPid());
268 ScopedDisableMsanInterceptorChecks S; // RmDirRecursive may call opendir().
269 RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
270 // Stop right now, don't perform any at-exit actions.
271 _Exit(Options.InterruptExitCode);
275 void Fuzzer::AlarmCallback() {
276 assert(Options.UnitTimeoutSec > 0);
277 // In Windows and Fuchsia, Alarm callback is executed by a different thread.
278 // NetBSD's current behavior needs this change too.
279 #if !LIBFUZZER_WINDOWS && !LIBFUZZER_NETBSD && !LIBFUZZER_FUCHSIA
280 if (!InFuzzingThread())
283 if (!RunningUserCallback)
284 return; // We have not started running units yet.
286 duration_cast<seconds>(system_clock::now() - UnitStartTime).count();
289 if (Options.Verbosity >= 2)
290 Printf("AlarmCallback %zd\n", Seconds);
291 if (Seconds >= (size_t)Options.UnitTimeoutSec) {
292 if (EF->__sanitizer_acquire_crash_state &&
293 !EF->__sanitizer_acquire_crash_state())
295 Printf("ALARM: working on the last Unit for %zd seconds\n", Seconds);
296 Printf(" and the timeout value is %d (use -timeout=N to change)\n",
297 Options.UnitTimeoutSec);
298 DumpCurrentUnit("timeout-");
299 Printf("==%lu== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
302 Printf("SUMMARY: libFuzzer: timeout\n");
304 _Exit(Options.TimeoutExitCode); // Stop right now.
308 void Fuzzer::RssLimitCallback() {
309 if (EF->__sanitizer_acquire_crash_state &&
310 !EF->__sanitizer_acquire_crash_state())
313 "==%lu== ERROR: libFuzzer: out-of-memory (used: %zdMb; limit: %zdMb)\n",
314 GetPid(), GetPeakRSSMb(), Options.RssLimitMb);
315 Printf(" To change the out-of-memory limit use -rss_limit_mb=<N>\n\n");
316 PrintMemoryProfile();
317 DumpCurrentUnit("oom-");
318 Printf("SUMMARY: libFuzzer: out-of-memory\n");
320 _Exit(Options.OOMExitCode); // Stop right now.
323 void Fuzzer::PrintStats(const char *Where, const char *End, size_t Units,
325 size_t ExecPerSec = execPerSec();
326 if (!Options.Verbosity)
328 Printf("#%zd\t%s", TotalNumberOfRuns, Where);
329 if (size_t N = TPC.GetTotalPCCoverage())
330 Printf(" cov: %zd", N);
331 if (size_t N = Features ? Features : Corpus.NumFeatures())
332 Printf(" ft: %zd", N);
333 if (!Corpus.empty()) {
334 Printf(" corp: %zd", Corpus.NumActiveUnits());
335 if (size_t N = Corpus.SizeInBytes()) {
338 else if (N < (1 << 24))
339 Printf("/%zdKb", N >> 10);
341 Printf("/%zdMb", N >> 20);
343 if (size_t FF = Corpus.NumInputsThatTouchFocusFunction())
344 Printf(" focus: %zd", FF);
346 if (TmpMaxMutationLen)
347 Printf(" lim: %zd", TmpMaxMutationLen);
349 Printf(" units: %zd", Units);
351 Printf(" exec/s: %zd", ExecPerSec);
352 Printf(" rss: %zdMb", GetPeakRSSMb());
356 void Fuzzer::PrintFinalStats() {
357 if (Options.PrintCoverage)
359 if (Options.PrintCorpusStats)
361 if (!Options.PrintFinalStats)
363 size_t ExecPerSec = execPerSec();
364 Printf("stat::number_of_executed_units: %zd\n", TotalNumberOfRuns);
365 Printf("stat::average_exec_per_sec: %zd\n", ExecPerSec);
366 Printf("stat::new_units_added: %zd\n", NumberOfNewUnitsAdded);
367 Printf("stat::slowest_unit_time_sec: %zd\n", TimeOfLongestUnitInSeconds);
368 Printf("stat::peak_rss_mb: %zd\n", GetPeakRSSMb());
371 void Fuzzer::SetMaxInputLen(size_t MaxInputLen) {
372 assert(this->MaxInputLen == 0); // Can only reset MaxInputLen from 0 to non-0.
374 this->MaxInputLen = MaxInputLen;
375 this->MaxMutationLen = MaxInputLen;
376 AllocateCurrentUnitData();
377 Printf("INFO: -max_len is not provided; "
378 "libFuzzer will not generate inputs larger than %zd bytes\n",
382 void Fuzzer::SetMaxMutationLen(size_t MaxMutationLen) {
383 assert(MaxMutationLen && MaxMutationLen <= MaxInputLen);
384 this->MaxMutationLen = MaxMutationLen;
387 void Fuzzer::CheckExitOnSrcPosOrItem() {
388 if (!Options.ExitOnSrcPos.empty()) {
389 static auto *PCsSet = new Set<uintptr_t>;
390 auto HandlePC = [&](const TracePC::PCTableEntry *TE) {
391 if (!PCsSet->insert(TE->PC).second)
393 std::string Descr = DescribePC("%F %L", TE->PC + 1);
394 if (Descr.find(Options.ExitOnSrcPos) != std::string::npos) {
395 Printf("INFO: found line matching '%s', exiting.\n",
396 Options.ExitOnSrcPos.c_str());
400 TPC.ForEachObservedPC(HandlePC);
402 if (!Options.ExitOnItem.empty()) {
403 if (Corpus.HasUnit(Options.ExitOnItem)) {
404 Printf("INFO: found item with checksum '%s', exiting.\n",
405 Options.ExitOnItem.c_str());
411 void Fuzzer::RereadOutputCorpus(size_t MaxSize) {
412 if (Options.OutputCorpus.empty() || !Options.ReloadIntervalSec)
414 Vector<Unit> AdditionalCorpus;
415 ReadDirToVectorOfUnits(Options.OutputCorpus.c_str(), &AdditionalCorpus,
416 &EpochOfLastReadOfOutputCorpus, MaxSize,
417 /*ExitOnError*/ false);
418 if (Options.Verbosity >= 2)
419 Printf("Reload: read %zd new units.\n", AdditionalCorpus.size());
420 bool Reloaded = false;
421 for (auto &U : AdditionalCorpus) {
422 if (U.size() > MaxSize)
424 if (!Corpus.HasUnit(U)) {
425 if (RunOne(U.data(), U.size())) {
426 CheckExitOnSrcPosOrItem();
432 PrintStats("RELOAD");
435 void Fuzzer::PrintPulseAndReportSlowInput(const uint8_t *Data, size_t Size) {
437 duration_cast<seconds>(UnitStopTime - UnitStartTime).count();
438 if (!(TotalNumberOfRuns & (TotalNumberOfRuns - 1)) &&
439 secondsSinceProcessStartUp() >= 2)
440 PrintStats("pulse ");
441 if (TimeOfUnit > TimeOfLongestUnitInSeconds * 1.1 &&
442 TimeOfUnit >= Options.ReportSlowUnits) {
443 TimeOfLongestUnitInSeconds = TimeOfUnit;
444 Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
445 WriteUnitToFileWithPrefix({Data, Data + Size}, "slow-unit-");
449 static void WriteFeatureSetToFile(const std::string &FeaturesDir,
450 const std::string &FileName,
451 const Vector<uint32_t> &FeatureSet) {
452 if (FeaturesDir.empty() || FeatureSet.empty()) return;
453 WriteToFile(reinterpret_cast<const uint8_t *>(FeatureSet.data()),
454 FeatureSet.size() * sizeof(FeatureSet[0]),
455 DirPlusFile(FeaturesDir, FileName));
458 static void RenameFeatureSetFile(const std::string &FeaturesDir,
459 const std::string &OldFile,
460 const std::string &NewFile) {
461 if (FeaturesDir.empty()) return;
462 RenameFile(DirPlusFile(FeaturesDir, OldFile),
463 DirPlusFile(FeaturesDir, NewFile));
466 bool Fuzzer::RunOne(const uint8_t *Data, size_t Size, bool MayDeleteFile,
467 InputInfo *II, bool *FoundUniqFeatures) {
471 ExecuteCallback(Data, Size);
473 UniqFeatureSetTmp.clear();
474 size_t FoundUniqFeaturesOfII = 0;
475 size_t NumUpdatesBefore = Corpus.NumFeatureUpdates();
476 TPC.CollectFeatures([&](size_t Feature) {
477 if (Corpus.AddFeature(Feature, Size, Options.Shrink))
478 UniqFeatureSetTmp.push_back(Feature);
479 if (Options.Entropic)
480 Corpus.UpdateFeatureFrequency(II, Feature);
481 if (Options.ReduceInputs && II)
482 if (std::binary_search(II->UniqFeatureSet.begin(),
483 II->UniqFeatureSet.end(), Feature))
484 FoundUniqFeaturesOfII++;
486 if (FoundUniqFeatures)
487 *FoundUniqFeatures = FoundUniqFeaturesOfII;
488 PrintPulseAndReportSlowInput(Data, Size);
489 size_t NumNewFeatures = Corpus.NumFeatureUpdates() - NumUpdatesBefore;
490 if (NumNewFeatures) {
491 TPC.UpdateObservedPCs();
492 auto NewII = Corpus.AddToCorpus({Data, Data + Size}, NumNewFeatures,
493 MayDeleteFile, TPC.ObservedFocusFunction(),
494 UniqFeatureSetTmp, DFT, II);
495 WriteFeatureSetToFile(Options.FeaturesDir, Sha1ToString(NewII->Sha1),
496 NewII->UniqFeatureSet);
499 if (II && FoundUniqFeaturesOfII &&
500 II->DataFlowTraceForFocusFunction.empty() &&
501 FoundUniqFeaturesOfII == II->UniqFeatureSet.size() &&
502 II->U.size() > Size) {
503 auto OldFeaturesFile = Sha1ToString(II->Sha1);
504 Corpus.Replace(II, {Data, Data + Size});
505 RenameFeatureSetFile(Options.FeaturesDir, OldFeaturesFile,
506 Sha1ToString(II->Sha1));
512 size_t Fuzzer::GetCurrentUnitInFuzzingThead(const uint8_t **Data) const {
513 assert(InFuzzingThread());
514 *Data = CurrentUnitData;
515 return CurrentUnitSize;
518 void Fuzzer::CrashOnOverwrittenData() {
519 Printf("==%d== ERROR: libFuzzer: fuzz target overwrites its const input\n",
522 Printf("SUMMARY: libFuzzer: overwrites-const-input\n");
523 DumpCurrentUnit("crash-");
525 _Exit(Options.ErrorExitCode); // Stop right now.
528 // Compare two arrays, but not all bytes if the arrays are large.
529 static bool LooseMemeq(const uint8_t *A, const uint8_t *B, size_t Size) {
530 const size_t Limit = 64;
532 return !memcmp(A, B, Size);
533 // Compare first and last Limit/2 bytes.
534 return !memcmp(A, B, Limit / 2) &&
535 !memcmp(A + Size - Limit / 2, B + Size - Limit / 2, Limit / 2);
538 void Fuzzer::ExecuteCallback(const uint8_t *Data, size_t Size) {
539 TPC.RecordInitialStack();
541 assert(InFuzzingThread());
542 // We copy the contents of Unit into a separate heap buffer
543 // so that we reliably find buffer overflows in it.
544 uint8_t *DataCopy = new uint8_t[Size];
545 memcpy(DataCopy, Data, Size);
546 if (EF->__msan_unpoison)
547 EF->__msan_unpoison(DataCopy, Size);
548 if (EF->__msan_unpoison_param)
549 EF->__msan_unpoison_param(2);
550 if (CurrentUnitData && CurrentUnitData != Data)
551 memcpy(CurrentUnitData, Data, Size);
552 CurrentUnitSize = Size;
554 ScopedEnableMsanInterceptorChecks S;
555 AllocTracer.Start(Options.TraceMalloc);
556 UnitStartTime = system_clock::now();
558 RunningUserCallback = true;
559 int Res = CB(DataCopy, Size);
560 RunningUserCallback = false;
561 UnitStopTime = system_clock::now();
564 HasMoreMallocsThanFrees = AllocTracer.Stop();
566 if (!LooseMemeq(DataCopy, Data, Size))
567 CrashOnOverwrittenData();
572 std::string Fuzzer::WriteToOutputCorpus(const Unit &U) {
573 if (Options.OnlyASCII)
575 if (Options.OutputCorpus.empty())
577 std::string Path = DirPlusFile(Options.OutputCorpus, Hash(U));
578 WriteToFile(U, Path);
579 if (Options.Verbosity >= 2)
580 Printf("Written %zd bytes to %s\n", U.size(), Path.c_str());
584 void Fuzzer::WriteUnitToFileWithPrefix(const Unit &U, const char *Prefix) {
585 if (!Options.SaveArtifacts)
587 std::string Path = Options.ArtifactPrefix + Prefix + Hash(U);
588 if (!Options.ExactArtifactPath.empty())
589 Path = Options.ExactArtifactPath; // Overrides ArtifactPrefix.
590 WriteToFile(U, Path);
591 Printf("artifact_prefix='%s'; Test unit written to %s\n",
592 Options.ArtifactPrefix.c_str(), Path.c_str());
593 if (U.size() <= kMaxUnitSizeToPrint)
594 Printf("Base64: %s\n", Base64(U).c_str());
597 void Fuzzer::PrintStatusForNewUnit(const Unit &U, const char *Text) {
598 if (!Options.PrintNEW)
600 PrintStats(Text, "");
601 if (Options.Verbosity) {
602 Printf(" L: %zd/%zd ", U.size(), Corpus.MaxInputSize());
603 MD.PrintMutationSequence();
608 void Fuzzer::ReportNewCoverage(InputInfo *II, const Unit &U) {
609 II->NumSuccessfullMutations++;
610 MD.RecordSuccessfulMutationSequence();
611 PrintStatusForNewUnit(U, II->Reduced ? "REDUCE" : "NEW ");
612 WriteToOutputCorpus(U);
613 NumberOfNewUnitsAdded++;
614 CheckExitOnSrcPosOrItem(); // Check only after the unit is saved to corpus.
615 LastCorpusUpdateRun = TotalNumberOfRuns;
618 // Tries detecting a memory leak on the particular input that we have just
619 // executed before calling this function.
620 void Fuzzer::TryDetectingAMemoryLeak(const uint8_t *Data, size_t Size,
621 bool DuringInitialCorpusExecution) {
622 if (!HasMoreMallocsThanFrees)
623 return; // mallocs==frees, a leak is unlikely.
624 if (!Options.DetectLeaks)
626 if (!DuringInitialCorpusExecution &&
627 TotalNumberOfRuns >= Options.MaxNumberOfRuns)
629 if (!&(EF->__lsan_enable) || !&(EF->__lsan_disable) ||
630 !(EF->__lsan_do_recoverable_leak_check))
632 // Run the target once again, but with lsan disabled so that if there is
633 // a real leak we do not report it twice.
634 EF->__lsan_disable();
635 ExecuteCallback(Data, Size);
637 if (!HasMoreMallocsThanFrees)
638 return; // a leak is unlikely.
639 if (NumberOfLeakDetectionAttempts++ > 1000) {
640 Options.DetectLeaks = false;
641 Printf("INFO: libFuzzer disabled leak detection after every mutation.\n"
642 " Most likely the target function accumulates allocated\n"
643 " memory in a global state w/o actually leaking it.\n"
644 " You may try running this binary with -trace_malloc=[12]"
645 " to get a trace of mallocs and frees.\n"
646 " If LeakSanitizer is enabled in this process it will still\n"
647 " run on the process shutdown.\n");
650 // Now perform the actual lsan pass. This is expensive and we must ensure
651 // we don't call it too often.
652 if (EF->__lsan_do_recoverable_leak_check()) { // Leak is found, report it.
653 if (DuringInitialCorpusExecution)
654 Printf("\nINFO: a leak has been found in the initial corpus.\n\n");
655 Printf("INFO: to ignore leaks on libFuzzer side use -detect_leaks=0.\n\n");
656 CurrentUnitSize = Size;
657 DumpCurrentUnit("leak-");
659 _Exit(Options.ErrorExitCode); // not exit() to disable lsan further on.
663 void Fuzzer::MutateAndTestOne() {
664 MD.StartMutationSequence();
666 auto &II = Corpus.ChooseUnitToMutate(MD.GetRand());
667 if (Options.DoCrossOver)
668 MD.SetCrossOverWith(&Corpus.ChooseUnitToMutate(MD.GetRand()).U);
669 const auto &U = II.U;
670 memcpy(BaseSha1, II.Sha1, sizeof(BaseSha1));
671 assert(CurrentUnitData);
672 size_t Size = U.size();
673 assert(Size <= MaxInputLen && "Oversized Unit");
674 memcpy(CurrentUnitData, U.data(), Size);
676 assert(MaxMutationLen > 0);
678 size_t CurrentMaxMutationLen =
679 Min(MaxMutationLen, Max(U.size(), TmpMaxMutationLen));
680 assert(CurrentMaxMutationLen > 0);
682 for (int i = 0; i < Options.MutateDepth; i++) {
683 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
685 MaybeExitGracefully();
687 if (II.HasFocusFunction && !II.DataFlowTraceForFocusFunction.empty() &&
688 Size <= CurrentMaxMutationLen)
689 NewSize = MD.MutateWithMask(CurrentUnitData, Size, Size,
690 II.DataFlowTraceForFocusFunction);
692 // If MutateWithMask either failed or wasn't called, call default Mutate.
694 NewSize = MD.Mutate(CurrentUnitData, Size, CurrentMaxMutationLen);
695 assert(NewSize > 0 && "Mutator returned empty unit");
696 assert(NewSize <= CurrentMaxMutationLen && "Mutator return oversized unit");
698 II.NumExecutedMutations++;
699 Corpus.IncrementNumExecutedMutations();
701 bool FoundUniqFeatures = false;
702 bool NewCov = RunOne(CurrentUnitData, Size, /*MayDeleteFile=*/true, &II,
704 TryDetectingAMemoryLeak(CurrentUnitData, Size,
705 /*DuringInitialCorpusExecution*/ false);
707 ReportNewCoverage(&II, {CurrentUnitData, CurrentUnitData + Size});
708 break; // We will mutate this input more in the next rounds.
710 if (Options.ReduceDepth && !FoundUniqFeatures)
714 II.NeedsEnergyUpdate = true;
717 void Fuzzer::PurgeAllocator() {
718 if (Options.PurgeAllocatorIntervalSec < 0 || !EF->__sanitizer_purge_allocator)
720 if (duration_cast<seconds>(system_clock::now() -
721 LastAllocatorPurgeAttemptTime)
722 .count() < Options.PurgeAllocatorIntervalSec)
725 if (Options.RssLimitMb <= 0 ||
726 GetPeakRSSMb() > static_cast<size_t>(Options.RssLimitMb) / 2)
727 EF->__sanitizer_purge_allocator();
729 LastAllocatorPurgeAttemptTime = system_clock::now();
732 void Fuzzer::ReadAndExecuteSeedCorpora(Vector<SizedFile> &CorporaFiles) {
733 const size_t kMaxSaneLen = 1 << 20;
734 const size_t kMinDefaultLen = 4096;
737 size_t TotalSize = 0;
738 for (auto &File : CorporaFiles) {
739 MaxSize = Max(File.Size, MaxSize);
740 MinSize = Min(File.Size, MinSize);
741 TotalSize += File.Size;
743 if (Options.MaxLen == 0)
744 SetMaxInputLen(std::min(std::max(kMinDefaultLen, MaxSize), kMaxSaneLen));
745 assert(MaxInputLen > 0);
747 // Test the callback with empty input and never try it again.
749 ExecuteCallback(&dummy, 0);
751 if (CorporaFiles.empty()) {
752 Printf("INFO: A corpus is not provided, starting from an empty corpus\n");
753 Unit U({'\n'}); // Valid ASCII input.
754 RunOne(U.data(), U.size());
756 Printf("INFO: seed corpus: files: %zd min: %zdb max: %zdb total: %zdb"
758 CorporaFiles.size(), MinSize, MaxSize, TotalSize, GetPeakRSSMb());
759 if (Options.ShuffleAtStartUp)
760 std::shuffle(CorporaFiles.begin(), CorporaFiles.end(), MD.GetRand());
762 if (Options.PreferSmall) {
763 std::stable_sort(CorporaFiles.begin(), CorporaFiles.end());
764 assert(CorporaFiles.front().Size <= CorporaFiles.back().Size);
767 // Load and execute inputs one by one.
768 for (auto &SF : CorporaFiles) {
769 auto U = FileToVector(SF.File, MaxInputLen, /*ExitOnError=*/false);
770 assert(U.size() <= MaxInputLen);
771 RunOne(U.data(), U.size());
772 CheckExitOnSrcPosOrItem();
773 TryDetectingAMemoryLeak(U.data(), U.size(),
774 /*DuringInitialCorpusExecution*/ true);
778 PrintStats("INITED");
779 if (!Options.FocusFunction.empty()) {
780 Printf("INFO: %zd/%zd inputs touch the focus function\n",
781 Corpus.NumInputsThatTouchFocusFunction(), Corpus.size());
782 if (!Options.DataFlowTrace.empty())
783 Printf("INFO: %zd/%zd inputs have the Data Flow Trace\n",
784 Corpus.NumInputsWithDataFlowTrace(),
785 Corpus.NumInputsThatTouchFocusFunction());
788 if (Corpus.empty() && Options.MaxNumberOfRuns) {
789 Printf("ERROR: no interesting inputs were found. "
790 "Is the code instrumented for coverage? Exiting.\n");
795 void Fuzzer::Loop(Vector<SizedFile> &CorporaFiles) {
796 auto FocusFunctionOrAuto = Options.FocusFunction;
797 DFT.Init(Options.DataFlowTrace, &FocusFunctionOrAuto, CorporaFiles,
799 TPC.SetFocusFunction(FocusFunctionOrAuto);
800 ReadAndExecuteSeedCorpora(CorporaFiles);
801 DFT.Clear(); // No need for DFT any more.
802 TPC.SetPrintNewPCs(Options.PrintNewCovPcs);
803 TPC.SetPrintNewFuncs(Options.PrintNewCovFuncs);
804 system_clock::time_point LastCorpusReload = system_clock::now();
807 Min(MaxMutationLen, Max(size_t(4), Corpus.MaxInputSize()));
810 auto Now = system_clock::now();
811 if (!Options.StopFile.empty() &&
812 !FileToVector(Options.StopFile, 1, false).empty())
814 if (duration_cast<seconds>(Now - LastCorpusReload).count() >=
815 Options.ReloadIntervalSec) {
816 RereadOutputCorpus(MaxInputLen);
817 LastCorpusReload = system_clock::now();
819 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
824 // Update TmpMaxMutationLen
825 if (Options.LenControl) {
826 if (TmpMaxMutationLen < MaxMutationLen &&
827 TotalNumberOfRuns - LastCorpusUpdateRun >
828 Options.LenControl * Log(TmpMaxMutationLen)) {
830 Min(MaxMutationLen, TmpMaxMutationLen + Log(TmpMaxMutationLen));
831 LastCorpusUpdateRun = TotalNumberOfRuns;
834 TmpMaxMutationLen = MaxMutationLen;
837 // Perform several mutations and runs.
843 PrintStats("DONE ", "\n");
844 MD.PrintRecommendedDictionary();
847 void Fuzzer::MinimizeCrashLoop(const Unit &U) {
850 while (!TimedOut() && TotalNumberOfRuns < Options.MaxNumberOfRuns) {
851 MD.StartMutationSequence();
852 memcpy(CurrentUnitData, U.data(), U.size());
853 for (int i = 0; i < Options.MutateDepth; i++) {
854 size_t NewSize = MD.Mutate(CurrentUnitData, U.size(), MaxMutationLen);
855 assert(NewSize > 0 && NewSize <= MaxMutationLen);
856 ExecuteCallback(CurrentUnitData, NewSize);
857 PrintPulseAndReportSlowInput(CurrentUnitData, NewSize);
858 TryDetectingAMemoryLeak(CurrentUnitData, NewSize,
859 /*DuringInitialCorpusExecution*/ false);
864 } // namespace fuzzer
868 ATTRIBUTE_INTERFACE size_t
869 LLVMFuzzerMutate(uint8_t *Data, size_t Size, size_t MaxSize) {
871 return fuzzer::F->GetMD().DefaultMutate(Data, Size, MaxSize);