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 "FuzzerRandom.h"
16 #include "FuzzerTracePC.h"
23 #if defined(__has_include)
24 #if __has_include(<sanitizer / lsan_interface.h>)
25 #include <sanitizer/lsan_interface.h>
29 #define NO_SANITIZE_MEMORY
30 #if defined(__has_feature)
31 #if __has_feature(memory_sanitizer)
32 #undef NO_SANITIZE_MEMORY
33 #define NO_SANITIZE_MEMORY __attribute__((no_sanitize_memory))
38 static const size_t kMaxUnitSizeToPrint = 256;
40 thread_local bool Fuzzer::IsMyThread;
42 bool RunningUserCallback = false;
44 // Only one Fuzzer per process.
47 // Leak detection is expensive, so we first check if there were more mallocs
48 // than frees (using the sanitizer malloc hooks) and only then try to call lsan.
49 struct MallocFreeTracer {
50 void Start(int TraceLevel) {
51 this->TraceLevel = TraceLevel;
53 Printf("MallocFreeTracer: START\n");
57 // Returns true if there were more mallocs than frees.
60 Printf("MallocFreeTracer: STOP %zd %zd (%s)\n", Mallocs.load(),
61 Frees.load(), Mallocs == Frees ? "same" : "DIFFERENT");
62 bool Result = Mallocs > Frees;
68 std::atomic<size_t> Mallocs;
69 std::atomic<size_t> Frees;
72 std::recursive_mutex TraceMutex;
73 bool TraceDisabled = false;
76 static MallocFreeTracer AllocTracer;
78 // Locks printing and avoids nested hooks triggered from mallocs/frees in
82 TraceLock() : Lock(AllocTracer.TraceMutex) {
83 AllocTracer.TraceDisabled = !AllocTracer.TraceDisabled;
85 ~TraceLock() { AllocTracer.TraceDisabled = !AllocTracer.TraceDisabled; }
87 bool IsDisabled() const {
88 // This is already inverted value.
89 return !AllocTracer.TraceDisabled;
93 std::lock_guard<std::recursive_mutex> Lock;
96 ATTRIBUTE_NO_SANITIZE_MEMORY
97 void MallocHook(const volatile void *ptr, size_t size) {
98 size_t N = AllocTracer.Mallocs++;
99 F->HandleMalloc(size);
100 if (int TraceLevel = AllocTracer.TraceLevel) {
102 if (Lock.IsDisabled())
104 Printf("MALLOC[%zd] %p %zd\n", N, ptr, size);
105 if (TraceLevel >= 2 && EF)
110 ATTRIBUTE_NO_SANITIZE_MEMORY
111 void FreeHook(const volatile void *ptr) {
112 size_t N = AllocTracer.Frees++;
113 if (int TraceLevel = AllocTracer.TraceLevel) {
115 if (Lock.IsDisabled())
117 Printf("FREE[%zd] %p\n", N, ptr);
118 if (TraceLevel >= 2 && EF)
123 // Crash on a single malloc that exceeds the rss limit.
124 void Fuzzer::HandleMalloc(size_t Size) {
125 if (!Options.MallocLimitMb || (Size >> 20) < (size_t)Options.MallocLimitMb)
127 Printf("==%d== ERROR: libFuzzer: out-of-memory (malloc(%zd))\n", GetPid(),
129 Printf(" To change the out-of-memory limit use -rss_limit_mb=<N>\n\n");
131 DumpCurrentUnit("oom-");
132 Printf("SUMMARY: libFuzzer: out-of-memory\n");
134 _Exit(Options.OOMExitCode); // Stop right now.
137 Fuzzer::Fuzzer(UserCallback CB, InputCorpus &Corpus, MutationDispatcher &MD,
138 FuzzingOptions Options)
139 : CB(CB), Corpus(Corpus), MD(MD), Options(Options) {
140 if (EF->__sanitizer_set_death_callback)
141 EF->__sanitizer_set_death_callback(StaticDeathCallback);
146 if (Options.DetectLeaks && EF->__sanitizer_install_malloc_and_free_hooks)
147 EF->__sanitizer_install_malloc_and_free_hooks(MallocHook, FreeHook);
148 TPC.SetUseCounters(Options.UseCounters);
149 TPC.SetUseValueProfileMask(Options.UseValueProfile);
151 if (Options.Verbosity)
152 TPC.PrintModuleInfo();
153 if (!Options.OutputCorpus.empty() && Options.ReloadIntervalSec)
154 EpochOfLastReadOfOutputCorpus = GetEpoch(Options.OutputCorpus);
155 MaxInputLen = MaxMutationLen = Options.MaxLen;
156 TmpMaxMutationLen = 0; // Will be set once we load the corpus.
157 AllocateCurrentUnitData();
159 memset(BaseSha1, 0, sizeof(BaseSha1));
164 void Fuzzer::AllocateCurrentUnitData() {
165 if (CurrentUnitData || MaxInputLen == 0)
167 CurrentUnitData = new uint8_t[MaxInputLen];
170 void Fuzzer::StaticDeathCallback() {
175 void Fuzzer::DumpCurrentUnit(const char *Prefix) {
176 if (!CurrentUnitData)
177 return; // Happens when running individual inputs.
178 ScopedDisableMsanInterceptorChecks S;
179 MD.PrintMutationSequence();
180 Printf("; base unit: %s\n", Sha1ToString(BaseSha1).c_str());
181 size_t UnitSize = CurrentUnitSize;
182 if (UnitSize <= kMaxUnitSizeToPrint) {
183 PrintHexArray(CurrentUnitData, UnitSize, "\n");
184 PrintASCII(CurrentUnitData, UnitSize, "\n");
186 WriteUnitToFileWithPrefix({CurrentUnitData, CurrentUnitData + UnitSize},
191 void Fuzzer::DeathCallback() {
192 DumpCurrentUnit("crash-");
196 void Fuzzer::StaticAlarmCallback() {
201 void Fuzzer::StaticCrashSignalCallback() {
206 void Fuzzer::StaticExitCallback() {
211 void Fuzzer::StaticInterruptCallback() {
213 F->InterruptCallback();
216 void Fuzzer::StaticGracefulExitCallback() {
218 F->GracefulExitRequested = true;
219 Printf("INFO: signal received, trying to exit gracefully\n");
222 void Fuzzer::StaticFileSizeExceedCallback() {
223 Printf("==%lu== ERROR: libFuzzer: file size exceeded\n", GetPid());
227 void Fuzzer::CrashCallback() {
228 if (EF->__sanitizer_acquire_crash_state &&
229 !EF->__sanitizer_acquire_crash_state())
231 Printf("==%lu== ERROR: libFuzzer: deadly signal\n", GetPid());
233 Printf("NOTE: libFuzzer has rudimentary signal handlers.\n"
234 " Combine libFuzzer with AddressSanitizer or similar for better "
236 Printf("SUMMARY: libFuzzer: deadly signal\n");
237 DumpCurrentUnit("crash-");
239 _Exit(Options.ErrorExitCode); // Stop right now.
242 void Fuzzer::ExitCallback() {
243 if (!RunningUserCallback)
244 return; // This exit did not come from the user callback
245 if (EF->__sanitizer_acquire_crash_state &&
246 !EF->__sanitizer_acquire_crash_state())
248 Printf("==%lu== ERROR: libFuzzer: fuzz target exited\n", GetPid());
250 Printf("SUMMARY: libFuzzer: fuzz target exited\n");
251 DumpCurrentUnit("crash-");
253 _Exit(Options.ErrorExitCode);
256 void Fuzzer::MaybeExitGracefully() {
257 if (!F->GracefulExitRequested) return;
258 Printf("==%lu== INFO: libFuzzer: exiting as requested\n", GetPid());
259 RmDirRecursive(TempPath(".dir"));
260 F->PrintFinalStats();
264 void Fuzzer::InterruptCallback() {
265 Printf("==%lu== libFuzzer: run interrupted; exiting\n", GetPid());
267 ScopedDisableMsanInterceptorChecks S; // RmDirRecursive may call opendir().
268 RmDirRecursive(TempPath(".dir"));
269 // Stop right now, don't perform any at-exit actions.
270 _Exit(Options.InterruptExitCode);
274 void Fuzzer::AlarmCallback() {
275 assert(Options.UnitTimeoutSec > 0);
276 // In Windows and Fuchsia, Alarm callback is executed by a different thread.
277 // NetBSD's current behavior needs this change too.
278 #if !LIBFUZZER_WINDOWS && !LIBFUZZER_NETBSD && !LIBFUZZER_FUCHSIA
279 if (!InFuzzingThread())
282 if (!RunningUserCallback)
283 return; // We have not started running units yet.
285 duration_cast<seconds>(system_clock::now() - UnitStartTime).count();
288 if (Options.Verbosity >= 2)
289 Printf("AlarmCallback %zd\n", Seconds);
290 if (Seconds >= (size_t)Options.UnitTimeoutSec) {
291 if (EF->__sanitizer_acquire_crash_state &&
292 !EF->__sanitizer_acquire_crash_state())
294 Printf("ALARM: working on the last Unit for %zd seconds\n", Seconds);
295 Printf(" and the timeout value is %d (use -timeout=N to change)\n",
296 Options.UnitTimeoutSec);
297 DumpCurrentUnit("timeout-");
298 Printf("==%lu== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
301 Printf("SUMMARY: libFuzzer: timeout\n");
303 _Exit(Options.TimeoutExitCode); // Stop right now.
307 void Fuzzer::RssLimitCallback() {
308 if (EF->__sanitizer_acquire_crash_state &&
309 !EF->__sanitizer_acquire_crash_state())
312 "==%lu== ERROR: libFuzzer: out-of-memory (used: %zdMb; limit: %zdMb)\n",
313 GetPid(), GetPeakRSSMb(), Options.RssLimitMb);
314 Printf(" To change the out-of-memory limit use -rss_limit_mb=<N>\n\n");
315 PrintMemoryProfile();
316 DumpCurrentUnit("oom-");
317 Printf("SUMMARY: libFuzzer: out-of-memory\n");
319 _Exit(Options.OOMExitCode); // Stop right now.
322 void Fuzzer::PrintStats(const char *Where, const char *End, size_t Units,
324 size_t ExecPerSec = execPerSec();
325 if (!Options.Verbosity)
327 Printf("#%zd\t%s", TotalNumberOfRuns, Where);
328 if (size_t N = TPC.GetTotalPCCoverage())
329 Printf(" cov: %zd", N);
330 if (size_t N = Features ? Features : Corpus.NumFeatures())
331 Printf(" ft: %zd", N);
332 if (!Corpus.empty()) {
333 Printf(" corp: %zd", Corpus.NumActiveUnits());
334 if (size_t N = Corpus.SizeInBytes()) {
337 else if (N < (1 << 24))
338 Printf("/%zdKb", N >> 10);
340 Printf("/%zdMb", N >> 20);
342 if (size_t FF = Corpus.NumInputsThatTouchFocusFunction())
343 Printf(" focus: %zd", FF);
345 if (TmpMaxMutationLen)
346 Printf(" lim: %zd", TmpMaxMutationLen);
348 Printf(" units: %zd", Units);
350 Printf(" exec/s: %zd", ExecPerSec);
351 Printf(" rss: %zdMb", GetPeakRSSMb());
355 void Fuzzer::PrintFinalStats() {
356 if (Options.PrintCoverage)
358 if (Options.PrintCorpusStats)
360 if (!Options.PrintFinalStats)
362 size_t ExecPerSec = execPerSec();
363 Printf("stat::number_of_executed_units: %zd\n", TotalNumberOfRuns);
364 Printf("stat::average_exec_per_sec: %zd\n", ExecPerSec);
365 Printf("stat::new_units_added: %zd\n", NumberOfNewUnitsAdded);
366 Printf("stat::slowest_unit_time_sec: %zd\n", TimeOfLongestUnitInSeconds);
367 Printf("stat::peak_rss_mb: %zd\n", GetPeakRSSMb());
370 void Fuzzer::SetMaxInputLen(size_t MaxInputLen) {
371 assert(this->MaxInputLen == 0); // Can only reset MaxInputLen from 0 to non-0.
373 this->MaxInputLen = MaxInputLen;
374 this->MaxMutationLen = MaxInputLen;
375 AllocateCurrentUnitData();
376 Printf("INFO: -max_len is not provided; "
377 "libFuzzer will not generate inputs larger than %zd bytes\n",
381 void Fuzzer::SetMaxMutationLen(size_t MaxMutationLen) {
382 assert(MaxMutationLen && MaxMutationLen <= MaxInputLen);
383 this->MaxMutationLen = MaxMutationLen;
386 void Fuzzer::CheckExitOnSrcPosOrItem() {
387 if (!Options.ExitOnSrcPos.empty()) {
388 static auto *PCsSet = new Set<uintptr_t>;
389 auto HandlePC = [&](const TracePC::PCTableEntry *TE) {
390 if (!PCsSet->insert(TE->PC).second)
392 std::string Descr = DescribePC("%F %L", TE->PC + 1);
393 if (Descr.find(Options.ExitOnSrcPos) != std::string::npos) {
394 Printf("INFO: found line matching '%s', exiting.\n",
395 Options.ExitOnSrcPos.c_str());
399 TPC.ForEachObservedPC(HandlePC);
401 if (!Options.ExitOnItem.empty()) {
402 if (Corpus.HasUnit(Options.ExitOnItem)) {
403 Printf("INFO: found item with checksum '%s', exiting.\n",
404 Options.ExitOnItem.c_str());
410 void Fuzzer::RereadOutputCorpus(size_t MaxSize) {
411 if (Options.OutputCorpus.empty() || !Options.ReloadIntervalSec)
413 Vector<Unit> AdditionalCorpus;
414 ReadDirToVectorOfUnits(Options.OutputCorpus.c_str(), &AdditionalCorpus,
415 &EpochOfLastReadOfOutputCorpus, MaxSize,
416 /*ExitOnError*/ false);
417 if (Options.Verbosity >= 2)
418 Printf("Reload: read %zd new units.\n", AdditionalCorpus.size());
419 bool Reloaded = false;
420 for (auto &U : AdditionalCorpus) {
421 if (U.size() > MaxSize)
423 if (!Corpus.HasUnit(U)) {
424 if (RunOne(U.data(), U.size())) {
425 CheckExitOnSrcPosOrItem();
431 PrintStats("RELOAD");
434 void Fuzzer::PrintPulseAndReportSlowInput(const uint8_t *Data, size_t Size) {
436 duration_cast<seconds>(UnitStopTime - UnitStartTime).count();
437 if (!(TotalNumberOfRuns & (TotalNumberOfRuns - 1)) &&
438 secondsSinceProcessStartUp() >= 2)
439 PrintStats("pulse ");
440 if (TimeOfUnit > TimeOfLongestUnitInSeconds * 1.1 &&
441 TimeOfUnit >= Options.ReportSlowUnits) {
442 TimeOfLongestUnitInSeconds = TimeOfUnit;
443 Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
444 WriteUnitToFileWithPrefix({Data, Data + Size}, "slow-unit-");
448 static void WriteFeatureSetToFile(const std::string &FeaturesDir,
449 const std::string &FileName,
450 const Vector<uint32_t> &FeatureSet) {
451 if (FeaturesDir.empty() || FeatureSet.empty()) return;
452 WriteToFile(reinterpret_cast<const uint8_t *>(FeatureSet.data()),
453 FeatureSet.size() * sizeof(FeatureSet[0]),
454 DirPlusFile(FeaturesDir, FileName));
457 static void RenameFeatureSetFile(const std::string &FeaturesDir,
458 const std::string &OldFile,
459 const std::string &NewFile) {
460 if (FeaturesDir.empty()) return;
461 RenameFile(DirPlusFile(FeaturesDir, OldFile),
462 DirPlusFile(FeaturesDir, NewFile));
465 bool Fuzzer::RunOne(const uint8_t *Data, size_t Size, bool MayDeleteFile,
466 InputInfo *II, bool *FoundUniqFeatures) {
470 ExecuteCallback(Data, Size);
472 UniqFeatureSetTmp.clear();
473 size_t FoundUniqFeaturesOfII = 0;
474 size_t NumUpdatesBefore = Corpus.NumFeatureUpdates();
475 TPC.CollectFeatures([&](size_t Feature) {
476 if (Corpus.AddFeature(Feature, Size, Options.Shrink))
477 UniqFeatureSetTmp.push_back(Feature);
478 if (Options.ReduceInputs && II)
479 if (std::binary_search(II->UniqFeatureSet.begin(),
480 II->UniqFeatureSet.end(), Feature))
481 FoundUniqFeaturesOfII++;
483 if (FoundUniqFeatures)
484 *FoundUniqFeatures = FoundUniqFeaturesOfII;
485 PrintPulseAndReportSlowInput(Data, Size);
486 size_t NumNewFeatures = Corpus.NumFeatureUpdates() - NumUpdatesBefore;
487 if (NumNewFeatures) {
488 TPC.UpdateObservedPCs();
489 auto NewII = Corpus.AddToCorpus({Data, Data + Size}, NumNewFeatures,
490 MayDeleteFile, TPC.ObservedFocusFunction(),
491 UniqFeatureSetTmp, DFT, II);
492 WriteFeatureSetToFile(Options.FeaturesDir, Sha1ToString(NewII->Sha1),
493 NewII->UniqFeatureSet);
496 if (II && FoundUniqFeaturesOfII &&
497 II->DataFlowTraceForFocusFunction.empty() &&
498 FoundUniqFeaturesOfII == II->UniqFeatureSet.size() &&
499 II->U.size() > Size) {
500 auto OldFeaturesFile = Sha1ToString(II->Sha1);
501 Corpus.Replace(II, {Data, Data + Size});
502 RenameFeatureSetFile(Options.FeaturesDir, OldFeaturesFile,
503 Sha1ToString(II->Sha1));
509 size_t Fuzzer::GetCurrentUnitInFuzzingThead(const uint8_t **Data) const {
510 assert(InFuzzingThread());
511 *Data = CurrentUnitData;
512 return CurrentUnitSize;
515 void Fuzzer::CrashOnOverwrittenData() {
516 Printf("==%d== ERROR: libFuzzer: fuzz target overwrites its const input\n",
519 Printf("SUMMARY: libFuzzer: overwrites-const-input\n");
520 DumpCurrentUnit("crash-");
522 _Exit(Options.ErrorExitCode); // Stop right now.
525 // Compare two arrays, but not all bytes if the arrays are large.
526 static bool LooseMemeq(const uint8_t *A, const uint8_t *B, size_t Size) {
527 const size_t Limit = 64;
529 return !memcmp(A, B, Size);
530 // Compare first and last Limit/2 bytes.
531 return !memcmp(A, B, Limit / 2) &&
532 !memcmp(A + Size - Limit / 2, B + Size - Limit / 2, Limit / 2);
535 void Fuzzer::ExecuteCallback(const uint8_t *Data, size_t Size) {
536 TPC.RecordInitialStack();
538 assert(InFuzzingThread());
539 // We copy the contents of Unit into a separate heap buffer
540 // so that we reliably find buffer overflows in it.
541 uint8_t *DataCopy = new uint8_t[Size];
542 memcpy(DataCopy, Data, Size);
543 if (EF->__msan_unpoison)
544 EF->__msan_unpoison(DataCopy, Size);
545 if (EF->__msan_unpoison_param)
546 EF->__msan_unpoison_param(2);
547 if (CurrentUnitData && CurrentUnitData != Data)
548 memcpy(CurrentUnitData, Data, Size);
549 CurrentUnitSize = Size;
551 ScopedEnableMsanInterceptorChecks S;
552 AllocTracer.Start(Options.TraceMalloc);
553 UnitStartTime = system_clock::now();
555 RunningUserCallback = true;
556 int Res = CB(DataCopy, Size);
557 RunningUserCallback = false;
558 UnitStopTime = system_clock::now();
561 HasMoreMallocsThanFrees = AllocTracer.Stop();
563 if (!LooseMemeq(DataCopy, Data, Size))
564 CrashOnOverwrittenData();
569 std::string Fuzzer::WriteToOutputCorpus(const Unit &U) {
570 if (Options.OnlyASCII)
572 if (Options.OutputCorpus.empty())
574 std::string Path = DirPlusFile(Options.OutputCorpus, Hash(U));
575 WriteToFile(U, Path);
576 if (Options.Verbosity >= 2)
577 Printf("Written %zd bytes to %s\n", U.size(), Path.c_str());
581 void Fuzzer::WriteUnitToFileWithPrefix(const Unit &U, const char *Prefix) {
582 if (!Options.SaveArtifacts)
584 std::string Path = Options.ArtifactPrefix + Prefix + Hash(U);
585 if (!Options.ExactArtifactPath.empty())
586 Path = Options.ExactArtifactPath; // Overrides ArtifactPrefix.
587 WriteToFile(U, Path);
588 Printf("artifact_prefix='%s'; Test unit written to %s\n",
589 Options.ArtifactPrefix.c_str(), Path.c_str());
590 if (U.size() <= kMaxUnitSizeToPrint)
591 Printf("Base64: %s\n", Base64(U).c_str());
594 void Fuzzer::PrintStatusForNewUnit(const Unit &U, const char *Text) {
595 if (!Options.PrintNEW)
597 PrintStats(Text, "");
598 if (Options.Verbosity) {
599 Printf(" L: %zd/%zd ", U.size(), Corpus.MaxInputSize());
600 MD.PrintMutationSequence();
605 void Fuzzer::ReportNewCoverage(InputInfo *II, const Unit &U) {
606 II->NumSuccessfullMutations++;
607 MD.RecordSuccessfulMutationSequence();
608 PrintStatusForNewUnit(U, II->Reduced ? "REDUCE" : "NEW ");
609 WriteToOutputCorpus(U);
610 NumberOfNewUnitsAdded++;
611 CheckExitOnSrcPosOrItem(); // Check only after the unit is saved to corpus.
612 LastCorpusUpdateRun = TotalNumberOfRuns;
615 // Tries detecting a memory leak on the particular input that we have just
616 // executed before calling this function.
617 void Fuzzer::TryDetectingAMemoryLeak(const uint8_t *Data, size_t Size,
618 bool DuringInitialCorpusExecution) {
619 if (!HasMoreMallocsThanFrees)
620 return; // mallocs==frees, a leak is unlikely.
621 if (!Options.DetectLeaks)
623 if (!DuringInitialCorpusExecution &&
624 TotalNumberOfRuns >= Options.MaxNumberOfRuns)
626 if (!&(EF->__lsan_enable) || !&(EF->__lsan_disable) ||
627 !(EF->__lsan_do_recoverable_leak_check))
629 // Run the target once again, but with lsan disabled so that if there is
630 // a real leak we do not report it twice.
631 EF->__lsan_disable();
632 ExecuteCallback(Data, Size);
634 if (!HasMoreMallocsThanFrees)
635 return; // a leak is unlikely.
636 if (NumberOfLeakDetectionAttempts++ > 1000) {
637 Options.DetectLeaks = false;
638 Printf("INFO: libFuzzer disabled leak detection after every mutation.\n"
639 " Most likely the target function accumulates allocated\n"
640 " memory in a global state w/o actually leaking it.\n"
641 " You may try running this binary with -trace_malloc=[12]"
642 " to get a trace of mallocs and frees.\n"
643 " If LeakSanitizer is enabled in this process it will still\n"
644 " run on the process shutdown.\n");
647 // Now perform the actual lsan pass. This is expensive and we must ensure
648 // we don't call it too often.
649 if (EF->__lsan_do_recoverable_leak_check()) { // Leak is found, report it.
650 if (DuringInitialCorpusExecution)
651 Printf("\nINFO: a leak has been found in the initial corpus.\n\n");
652 Printf("INFO: to ignore leaks on libFuzzer side use -detect_leaks=0.\n\n");
653 CurrentUnitSize = Size;
654 DumpCurrentUnit("leak-");
656 _Exit(Options.ErrorExitCode); // not exit() to disable lsan further on.
660 void Fuzzer::MutateAndTestOne() {
661 MD.StartMutationSequence();
663 auto &II = Corpus.ChooseUnitToMutate(MD.GetRand());
664 if (Options.DoCrossOver)
665 MD.SetCrossOverWith(&Corpus.ChooseUnitToMutate(MD.GetRand()).U);
666 const auto &U = II.U;
667 memcpy(BaseSha1, II.Sha1, sizeof(BaseSha1));
668 assert(CurrentUnitData);
669 size_t Size = U.size();
670 assert(Size <= MaxInputLen && "Oversized Unit");
671 memcpy(CurrentUnitData, U.data(), Size);
673 assert(MaxMutationLen > 0);
675 size_t CurrentMaxMutationLen =
676 Min(MaxMutationLen, Max(U.size(), TmpMaxMutationLen));
677 assert(CurrentMaxMutationLen > 0);
679 for (int i = 0; i < Options.MutateDepth; i++) {
680 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
682 MaybeExitGracefully();
684 if (II.HasFocusFunction && !II.DataFlowTraceForFocusFunction.empty() &&
685 Size <= CurrentMaxMutationLen)
686 NewSize = MD.MutateWithMask(CurrentUnitData, Size, Size,
687 II.DataFlowTraceForFocusFunction);
689 // If MutateWithMask either failed or wasn't called, call default Mutate.
691 NewSize = MD.Mutate(CurrentUnitData, Size, CurrentMaxMutationLen);
692 assert(NewSize > 0 && "Mutator returned empty unit");
693 assert(NewSize <= CurrentMaxMutationLen && "Mutator return oversized unit");
695 II.NumExecutedMutations++;
697 bool FoundUniqFeatures = false;
698 bool NewCov = RunOne(CurrentUnitData, Size, /*MayDeleteFile=*/true, &II,
700 TryDetectingAMemoryLeak(CurrentUnitData, Size,
701 /*DuringInitialCorpusExecution*/ false);
703 ReportNewCoverage(&II, {CurrentUnitData, CurrentUnitData + Size});
704 break; // We will mutate this input more in the next rounds.
706 if (Options.ReduceDepth && !FoundUniqFeatures)
711 void Fuzzer::PurgeAllocator() {
712 if (Options.PurgeAllocatorIntervalSec < 0 || !EF->__sanitizer_purge_allocator)
714 if (duration_cast<seconds>(system_clock::now() -
715 LastAllocatorPurgeAttemptTime)
716 .count() < Options.PurgeAllocatorIntervalSec)
719 if (Options.RssLimitMb <= 0 ||
720 GetPeakRSSMb() > static_cast<size_t>(Options.RssLimitMb) / 2)
721 EF->__sanitizer_purge_allocator();
723 LastAllocatorPurgeAttemptTime = system_clock::now();
726 void Fuzzer::ReadAndExecuteSeedCorpora(Vector<SizedFile> &CorporaFiles) {
727 const size_t kMaxSaneLen = 1 << 20;
728 const size_t kMinDefaultLen = 4096;
731 size_t TotalSize = 0;
732 for (auto &File : CorporaFiles) {
733 MaxSize = Max(File.Size, MaxSize);
734 MinSize = Min(File.Size, MinSize);
735 TotalSize += File.Size;
737 if (Options.MaxLen == 0)
738 SetMaxInputLen(std::min(std::max(kMinDefaultLen, MaxSize), kMaxSaneLen));
739 assert(MaxInputLen > 0);
741 // Test the callback with empty input and never try it again.
743 ExecuteCallback(&dummy, 0);
745 if (CorporaFiles.empty()) {
746 Printf("INFO: A corpus is not provided, starting from an empty corpus\n");
747 Unit U({'\n'}); // Valid ASCII input.
748 RunOne(U.data(), U.size());
750 Printf("INFO: seed corpus: files: %zd min: %zdb max: %zdb total: %zdb"
752 CorporaFiles.size(), MinSize, MaxSize, TotalSize, GetPeakRSSMb());
753 if (Options.ShuffleAtStartUp)
754 std::shuffle(CorporaFiles.begin(), CorporaFiles.end(), MD.GetRand());
756 if (Options.PreferSmall) {
757 std::stable_sort(CorporaFiles.begin(), CorporaFiles.end());
758 assert(CorporaFiles.front().Size <= CorporaFiles.back().Size);
761 // Load and execute inputs one by one.
762 for (auto &SF : CorporaFiles) {
763 auto U = FileToVector(SF.File, MaxInputLen, /*ExitOnError=*/false);
764 assert(U.size() <= MaxInputLen);
765 RunOne(U.data(), U.size());
766 CheckExitOnSrcPosOrItem();
767 TryDetectingAMemoryLeak(U.data(), U.size(),
768 /*DuringInitialCorpusExecution*/ true);
772 PrintStats("INITED");
773 if (!Options.FocusFunction.empty())
774 Printf("INFO: %zd/%zd inputs touch the focus function\n",
775 Corpus.NumInputsThatTouchFocusFunction(), Corpus.size());
776 if (!Options.DataFlowTrace.empty())
777 Printf("INFO: %zd/%zd inputs have the Data Flow Trace\n",
778 Corpus.NumInputsWithDataFlowTrace(), Corpus.size());
780 if (Corpus.empty() && Options.MaxNumberOfRuns) {
781 Printf("ERROR: no interesting inputs were found. "
782 "Is the code instrumented for coverage? Exiting.\n");
787 void Fuzzer::Loop(Vector<SizedFile> &CorporaFiles) {
788 auto FocusFunctionOrAuto = Options.FocusFunction;
789 DFT.Init(Options.DataFlowTrace, &FocusFunctionOrAuto, CorporaFiles,
791 TPC.SetFocusFunction(FocusFunctionOrAuto);
792 ReadAndExecuteSeedCorpora(CorporaFiles);
793 DFT.Clear(); // No need for DFT any more.
794 TPC.SetPrintNewPCs(Options.PrintNewCovPcs);
795 TPC.SetPrintNewFuncs(Options.PrintNewCovFuncs);
796 system_clock::time_point LastCorpusReload = system_clock::now();
799 Min(MaxMutationLen, Max(size_t(4), Corpus.MaxInputSize()));
802 auto Now = system_clock::now();
803 if (!Options.StopFile.empty() &&
804 !FileToVector(Options.StopFile, 1, false).empty())
806 if (duration_cast<seconds>(Now - LastCorpusReload).count() >=
807 Options.ReloadIntervalSec) {
808 RereadOutputCorpus(MaxInputLen);
809 LastCorpusReload = system_clock::now();
811 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
816 // Update TmpMaxMutationLen
817 if (Options.LenControl) {
818 if (TmpMaxMutationLen < MaxMutationLen &&
819 TotalNumberOfRuns - LastCorpusUpdateRun >
820 Options.LenControl * Log(TmpMaxMutationLen)) {
822 Min(MaxMutationLen, TmpMaxMutationLen + Log(TmpMaxMutationLen));
823 LastCorpusUpdateRun = TotalNumberOfRuns;
826 TmpMaxMutationLen = MaxMutationLen;
829 // Perform several mutations and runs.
835 PrintStats("DONE ", "\n");
836 MD.PrintRecommendedDictionary();
839 void Fuzzer::MinimizeCrashLoop(const Unit &U) {
842 while (!TimedOut() && TotalNumberOfRuns < Options.MaxNumberOfRuns) {
843 MD.StartMutationSequence();
844 memcpy(CurrentUnitData, U.data(), U.size());
845 for (int i = 0; i < Options.MutateDepth; i++) {
846 size_t NewSize = MD.Mutate(CurrentUnitData, U.size(), MaxMutationLen);
847 assert(NewSize > 0 && NewSize <= MaxMutationLen);
848 ExecuteCallback(CurrentUnitData, NewSize);
849 PrintPulseAndReportSlowInput(CurrentUnitData, NewSize);
850 TryDetectingAMemoryLeak(CurrentUnitData, NewSize,
851 /*DuringInitialCorpusExecution*/ false);
856 } // namespace fuzzer
860 ATTRIBUTE_INTERFACE size_t
861 LLVMFuzzerMutate(uint8_t *Data, size_t Size, size_t MaxSize) {
863 return fuzzer::F->GetMD().DefaultMutate(Data, Size, MaxSize);