1 //===- FuzzerLoop.cpp - Fuzzer's main loop --------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 //===----------------------------------------------------------------------===//
12 #include "FuzzerInternal.h"
15 #if defined(__has_include)
16 # if __has_include(<sanitizer/coverage_interface.h>)
17 # include <sanitizer/coverage_interface.h>
22 // Re-declare some of the sanitizer functions as "weak" so that
23 // libFuzzer can be linked w/o the sanitizers and sanitizer-coverage
24 // (in which case it will complain at start-up time).
25 __attribute__((weak)) void __sanitizer_print_stack_trace();
26 __attribute__((weak)) void __sanitizer_reset_coverage();
27 __attribute__((weak)) size_t __sanitizer_get_total_unique_caller_callee_pairs();
28 __attribute__((weak)) size_t __sanitizer_get_total_unique_coverage();
30 void __sanitizer_set_death_callback(void (*callback)(void));
31 __attribute__((weak)) size_t __sanitizer_get_number_of_counters();
33 uintptr_t __sanitizer_update_counter_bitset_and_clear_counters(uint8_t *bitset);
37 static const size_t kMaxUnitSizeToPrint = 256;
39 static void MissingWeakApiFunction(const char *FnName) {
40 Printf("ERROR: %s is not defined. Exiting.\n"
41 "Did you use -fsanitize-coverage=... to build your code?\n", FnName);
45 #define CHECK_WEAK_API_FUNCTION(fn) \
48 MissingWeakApiFunction(#fn); \
51 // Only one Fuzzer per process.
54 Fuzzer::Fuzzer(UserSuppliedFuzzer &USF, FuzzingOptions Options)
55 : USF(USF), Options(Options) {
57 InitializeTraceState();
62 void Fuzzer::SetDeathCallback() {
63 CHECK_WEAK_API_FUNCTION(__sanitizer_set_death_callback);
64 __sanitizer_set_death_callback(StaticDeathCallback);
67 void Fuzzer::PrintUnitInASCII(const Unit &U, const char *PrintAfter) {
68 PrintASCII(U, PrintAfter);
71 void Fuzzer::StaticDeathCallback() {
76 void Fuzzer::DeathCallback() {
78 if (CurrentUnit.size() <= kMaxUnitSizeToPrint) {
79 Print(CurrentUnit, "\n");
80 PrintUnitInASCII(CurrentUnit, "\n");
82 WriteUnitToFileWithPrefix(CurrentUnit, "crash-");
85 void Fuzzer::StaticAlarmCallback() {
90 void Fuzzer::AlarmCallback() {
91 assert(Options.UnitTimeoutSec > 0);
93 duration_cast<seconds>(system_clock::now() - UnitStartTime).count();
94 if (Seconds == 0) return;
95 if (Options.Verbosity >= 2)
96 Printf("AlarmCallback %zd\n", Seconds);
97 if (Seconds >= (size_t)Options.UnitTimeoutSec) {
98 Printf("ALARM: working on the last Unit for %zd seconds\n", Seconds);
99 Printf(" and the timeout value is %d (use -timeout=N to change)\n",
100 Options.UnitTimeoutSec);
101 if (CurrentUnit.size() <= kMaxUnitSizeToPrint) {
102 Print(CurrentUnit, "\n");
103 PrintUnitInASCII(CurrentUnit, "\n");
105 WriteUnitToFileWithPrefix(CurrentUnit, "timeout-");
106 Printf("==%d== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
108 if (__sanitizer_print_stack_trace)
109 __sanitizer_print_stack_trace();
110 Printf("SUMMARY: libFuzzer: timeout\n");
115 void Fuzzer::PrintStats(const char *Where, const char *End) {
116 size_t Seconds = secondsSinceProcessStartUp();
117 size_t ExecPerSec = (Seconds ? TotalNumberOfRuns / Seconds : 0);
119 if (Options.OutputCSV) {
120 static bool csvHeaderPrinted = false;
121 if (!csvHeaderPrinted) {
122 csvHeaderPrinted = true;
123 Printf("runs,block_cov,bits,cc_cov,corpus,execs_per_sec,tbms,reason\n");
125 Printf("%zd,%zd,%zd,%zd,%zd,%zd,%zd,%s\n", TotalNumberOfRuns,
126 LastRecordedBlockCoverage, TotalBits(),
127 LastRecordedCallerCalleeCoverage, Corpus.size(), ExecPerSec,
128 TotalNumberOfExecutedTraceBasedMutations, Where);
131 if (!Options.Verbosity)
133 Printf("#%zd\t%s", TotalNumberOfRuns, Where);
134 if (LastRecordedBlockCoverage)
135 Printf(" cov: %zd", LastRecordedBlockCoverage);
136 if (auto TB = TotalBits())
137 Printf(" bits: %zd", TB);
138 if (LastRecordedCallerCalleeCoverage)
139 Printf(" indir: %zd", LastRecordedCallerCalleeCoverage);
140 Printf(" units: %zd exec/s: %zd", Corpus.size(), ExecPerSec);
141 if (TotalNumberOfExecutedTraceBasedMutations)
142 Printf(" tbm: %zd", TotalNumberOfExecutedTraceBasedMutations);
146 void Fuzzer::RereadOutputCorpus() {
147 if (Options.OutputCorpus.empty()) return;
148 std::vector<Unit> AdditionalCorpus;
149 ReadDirToVectorOfUnits(Options.OutputCorpus.c_str(), &AdditionalCorpus,
150 &EpochOfLastReadOfOutputCorpus);
151 if (Corpus.empty()) {
152 Corpus = AdditionalCorpus;
155 if (!Options.Reload) return;
156 if (Options.Verbosity >= 2)
157 Printf("Reload: read %zd new units.\n", AdditionalCorpus.size());
158 for (auto &X : AdditionalCorpus) {
159 if (X.size() > (size_t)Options.MaxLen)
160 X.resize(Options.MaxLen);
161 if (UnitHashesAddedToCorpus.insert(Hash(X)).second) {
163 CurrentUnit.insert(CurrentUnit.begin(), X.begin(), X.end());
164 if (RunOne(CurrentUnit)) {
166 PrintStats("RELOAD");
172 void Fuzzer::ShuffleAndMinimize() {
173 bool PreferSmall = (Options.PreferSmallDuringInitialShuffle == 1 ||
174 (Options.PreferSmallDuringInitialShuffle == -1 &&
175 USF.GetRand().RandBool()));
176 if (Options.Verbosity)
177 Printf("PreferSmall: %d\n", PreferSmall);
179 std::vector<Unit> NewCorpus;
180 if (Options.ShuffleAtStartUp) {
181 std::random_shuffle(Corpus.begin(), Corpus.end(), USF.GetRand());
184 Corpus.begin(), Corpus.end(),
185 [](const Unit &A, const Unit &B) { return A.size() < B.size(); });
187 Unit &U = CurrentUnit;
188 for (const auto &C : Corpus) {
189 for (size_t First = 0; First < 1; First++) {
191 size_t Last = std::min(First + Options.MaxLen, C.size());
192 U.insert(U.begin(), C.begin() + First, C.begin() + Last);
193 if (Options.OnlyASCII)
196 NewCorpus.push_back(U);
197 if (Options.Verbosity >= 2)
198 Printf("NEW0: %zd L %zd\n", LastRecordedBlockCoverage, U.size());
203 for (auto &X : Corpus)
204 UnitHashesAddedToCorpus.insert(Hash(X));
205 PrintStats("INITED");
208 bool Fuzzer::RunOne(const Unit &U) {
209 UnitStartTime = system_clock::now();
212 PrepareCoverageBeforeRun();
214 bool Res = CheckCoverageAfterRun();
216 auto UnitStopTime = system_clock::now();
218 duration_cast<seconds>(UnitStopTime - UnitStartTime).count();
219 if (!(TotalNumberOfRuns & (TotalNumberOfRuns - 1)) &&
220 secondsSinceProcessStartUp() >= 2)
221 PrintStats("pulse ");
222 if (TimeOfUnit > TimeOfLongestUnitInSeconds &&
223 TimeOfUnit >= Options.ReportSlowUnits) {
224 TimeOfLongestUnitInSeconds = TimeOfUnit;
225 Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
226 WriteUnitToFileWithPrefix(U, "slow-unit-");
231 void Fuzzer::RunOneAndUpdateCorpus(Unit &U) {
232 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
234 if (Options.OnlyASCII)
237 ReportNewCoverage(U);
240 void Fuzzer::ExecuteCallback(const Unit &U) {
241 int Res = USF.TargetFunction(U.data(), U.size());
246 size_t Fuzzer::RecordBlockCoverage() {
247 CHECK_WEAK_API_FUNCTION(__sanitizer_get_total_unique_coverage);
248 return LastRecordedBlockCoverage = __sanitizer_get_total_unique_coverage();
251 size_t Fuzzer::RecordCallerCalleeCoverage() {
252 if (!Options.UseIndirCalls)
254 if (!__sanitizer_get_total_unique_caller_callee_pairs)
256 return LastRecordedCallerCalleeCoverage =
257 __sanitizer_get_total_unique_caller_callee_pairs();
260 void Fuzzer::PrepareCoverageBeforeRun() {
261 if (Options.UseCounters) {
262 size_t NumCounters = __sanitizer_get_number_of_counters();
263 CounterBitmap.resize(NumCounters);
264 __sanitizer_update_counter_bitset_and_clear_counters(0);
266 RecordBlockCoverage();
267 RecordCallerCalleeCoverage();
270 bool Fuzzer::CheckCoverageAfterRun() {
271 size_t OldCoverage = LastRecordedBlockCoverage;
272 size_t NewCoverage = RecordBlockCoverage();
273 size_t OldCallerCalleeCoverage = LastRecordedCallerCalleeCoverage;
274 size_t NewCallerCalleeCoverage = RecordCallerCalleeCoverage();
275 size_t NumNewBits = 0;
276 if (Options.UseCounters)
277 NumNewBits = __sanitizer_update_counter_bitset_and_clear_counters(
278 CounterBitmap.data());
279 return NewCoverage > OldCoverage ||
280 NewCallerCalleeCoverage > OldCallerCalleeCoverage || NumNewBits;
283 void Fuzzer::WriteToOutputCorpus(const Unit &U) {
284 if (Options.OutputCorpus.empty()) return;
285 std::string Path = DirPlusFile(Options.OutputCorpus, Hash(U));
286 WriteToFile(U, Path);
287 if (Options.Verbosity >= 2)
288 Printf("Written to %s\n", Path.c_str());
289 assert(!Options.OnlyASCII || IsASCII(U));
292 void Fuzzer::WriteUnitToFileWithPrefix(const Unit &U, const char *Prefix) {
293 if (!Options.SaveArtifacts)
295 std::string Path = Options.ArtifactPrefix + Prefix + Hash(U);
296 if (!Options.ExactArtifactPath.empty())
297 Path = Options.ExactArtifactPath; // Overrides ArtifactPrefix.
298 WriteToFile(U, Path);
299 Printf("artifact_prefix='%s'; Test unit written to %s\n",
300 Options.ArtifactPrefix.c_str(), Path.c_str());
301 if (U.size() <= kMaxUnitSizeToPrint) {
303 PrintFileAsBase64(Path);
307 void Fuzzer::SaveCorpus() {
308 if (Options.OutputCorpus.empty()) return;
309 for (const auto &U : Corpus)
310 WriteToFile(U, DirPlusFile(Options.OutputCorpus, Hash(U)));
311 if (Options.Verbosity)
312 Printf("Written corpus of %zd files to %s\n", Corpus.size(),
313 Options.OutputCorpus.c_str());
316 void Fuzzer::PrintStatusForNewUnit(const Unit &U) {
317 if (!Options.PrintNEW)
319 PrintStats("NEW ", "");
320 if (Options.Verbosity) {
321 Printf(" L: %zd", U.size());
324 PrintUnitInASCII(U, "\t");
331 void Fuzzer::ReportNewCoverage(const Unit &U) {
333 UnitHashesAddedToCorpus.insert(Hash(U));
334 PrintStatusForNewUnit(U);
335 WriteToOutputCorpus(U);
336 if (Options.ExitOnFirst)
340 void Fuzzer::Merge(const std::vector<std::string> &Corpora) {
341 if (Corpora.size() <= 1) {
342 Printf("Merge requires two or more corpus dirs\n");
345 auto InitialCorpusDir = Corpora[0];
346 ReadDir(InitialCorpusDir, nullptr);
347 Printf("Merge: running the initial corpus '%s' of %d units\n",
348 InitialCorpusDir.c_str(), Corpus.size());
349 for (auto &U : Corpus)
352 std::vector<std::string> ExtraCorpora(Corpora.begin() + 1, Corpora.end());
355 size_t NumMerged = 0;
356 for (auto &C : ExtraCorpora) {
359 Printf("Merge: merging the extra corpus '%s' of %zd units\n", C.c_str(),
361 for (auto &U : Corpus) {
364 WriteToOutputCorpus(U);
369 Printf("Merge: written %zd out of %zd units\n", NumMerged, NumTried);
372 void Fuzzer::MutateAndTestOne(Unit *U) {
373 for (int i = 0; i < Options.MutateDepth; i++) {
374 StartTraceRecording();
375 size_t Size = U->size();
376 U->resize(Options.MaxLen);
377 size_t NewSize = USF.Mutate(U->data(), Size, U->size());
378 assert(NewSize > 0 && "Mutator returned empty unit");
379 assert(NewSize <= (size_t)Options.MaxLen &&
380 "Mutator return overisized unit");
382 RunOneAndUpdateCorpus(*U);
383 size_t NumTraceBasedMutations = StopTraceRecording();
385 std::min((size_t)Options.TBMWidth, NumTraceBasedMutations);
387 std::min((size_t)Options.TBMDepth, NumTraceBasedMutations);
389 for (size_t w = 0; w < TBMWidth; w++) {
391 for (size_t d = 0; d < TBMDepth; d++) {
392 TotalNumberOfExecutedTraceBasedMutations++;
393 ApplyTraceBasedMutation(USF.GetRand()(NumTraceBasedMutations), U);
394 RunOneAndUpdateCorpus(*U);
400 // Returns an index of random unit from the corpus to mutate.
401 // Hypothesis: units added to the corpus last are more likely to be interesting.
402 // This function gives more wieght to the more recent units.
403 size_t Fuzzer::ChooseUnitIdxToMutate() {
404 size_t N = Corpus.size();
405 size_t Total = (N + 1) * N / 2;
406 size_t R = USF.GetRand()(Total);
407 size_t IdxBeg = 0, IdxEnd = N;
409 while (IdxEnd - IdxBeg >= 2) {
410 size_t Idx = IdxBeg + (IdxEnd - IdxBeg) / 2;
411 if (R > (Idx + 1) * Idx / 2)
420 // Experimental search heuristic: drilling.
421 // - Read, shuffle, execute and minimize the corpus.
422 // - Choose one random unit.
423 // - Reset the coverage.
424 // - Start fuzzing as if the chosen unit was the only element of the corpus.
425 // - When done, reset the coverage again.
426 // - Merge the newly created corpus into the original one.
427 void Fuzzer::Drill() {
428 // The corpus is already read, shuffled, and minimized.
429 assert(!Corpus.empty());
430 Options.PrintNEW = false; // Don't print NEW status lines when drilling.
432 Unit U = ChooseUnitToMutate();
434 CHECK_WEAK_API_FUNCTION(__sanitizer_reset_coverage);
435 __sanitizer_reset_coverage();
437 std::vector<Unit> SavedCorpus;
438 SavedCorpus.swap(Corpus);
440 assert(Corpus.size() == 1);
442 PrintStats("DRILL ");
443 std::string SavedOutputCorpusPath; // Don't write new units while drilling.
444 SavedOutputCorpusPath.swap(Options.OutputCorpus);
447 __sanitizer_reset_coverage();
449 PrintStats("REINIT");
450 SavedOutputCorpusPath.swap(Options.OutputCorpus);
451 for (auto &U : SavedCorpus)
453 PrintStats("MERGE ");
454 Options.PrintNEW = true;
455 size_t NumMerged = 0;
456 for (auto &U : Corpus) {
458 PrintStatusForNewUnit(U);
460 WriteToOutputCorpus(U);
463 PrintStats("MERGED");
464 if (NumMerged && Options.Verbosity)
465 Printf("Drilling discovered %zd new units\n", NumMerged);
468 void Fuzzer::Loop() {
470 size_t J1 = ChooseUnitIdxToMutate();;
472 RereadOutputCorpus();
473 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
475 if (Options.MaxTotalTimeSec > 0 &&
476 secondsSinceProcessStartUp() >
477 static_cast<size_t>(Options.MaxTotalTimeSec))
479 CurrentUnit = Corpus[J1];
480 // Optionally, cross with another unit.
481 if (Options.DoCrossOver && USF.GetRand().RandBool()) {
482 size_t J2 = ChooseUnitIdxToMutate();
483 if (!Corpus[J1].empty() && !Corpus[J2].empty()) {
484 assert(!Corpus[J2].empty());
485 CurrentUnit.resize(Options.MaxLen);
486 size_t NewSize = USF.CrossOver(
487 Corpus[J1].data(), Corpus[J1].size(), Corpus[J2].data(),
488 Corpus[J2].size(), CurrentUnit.data(), CurrentUnit.size());
489 assert(NewSize > 0 && "CrossOver returned empty unit");
490 assert(NewSize <= (size_t)Options.MaxLen &&
491 "CrossOver returned overisized unit");
492 CurrentUnit.resize(NewSize);
495 // Perform several mutations and runs.
496 MutateAndTestOne(&CurrentUnit);
499 PrintStats("DONE ", "\n");
502 void Fuzzer::SyncCorpus() {
503 if (Options.SyncCommand.empty() || Options.OutputCorpus.empty()) return;
504 auto Now = system_clock::now();
505 if (duration_cast<seconds>(Now - LastExternalSync).count() <
508 LastExternalSync = Now;
509 ExecuteCommand(Options.SyncCommand + " " + Options.OutputCorpus);
512 } // namespace fuzzer