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"
13 #include <sanitizer/coverage_interface.h>
17 // Re-declare some of the sanitizer functions as "weak" so that
18 // libFuzzer can be linked w/o the sanitizers and sanitizer-coveragte
19 // (in which case it will complain at start-up time).
20 __attribute__((weak)) void __sanitizer_print_stack_trace();
21 __attribute__((weak)) void __sanitizer_reset_coverage();
22 __attribute__((weak)) size_t __sanitizer_get_total_unique_caller_callee_pairs();
23 __attribute__((weak)) size_t __sanitizer_get_total_unique_coverage();
25 void __sanitizer_set_death_callback(void (*callback)(void));
26 __attribute__((weak)) size_t __sanitizer_get_number_of_counters();
28 uintptr_t __sanitizer_update_counter_bitset_and_clear_counters(uint8_t *bitset);
32 static const size_t kMaxUnitSizeToPrint = 256;
34 static void MissingWeakApiFunction(const char *FnName) {
35 Printf("ERROR: %s is not defined. Exiting.\n"
36 "Did you use -fsanitize-coverage=... to build your code?\n", FnName);
40 #define CHECK_WEAK_API_FUNCTION(fn) \
43 MissingWeakApiFunction(#fn); \
46 // Only one Fuzzer per process.
49 Fuzzer::Fuzzer(UserSuppliedFuzzer &USF, FuzzingOptions Options)
50 : USF(USF), Options(Options) {
52 InitializeTraceState();
57 void Fuzzer::SetDeathCallback() {
58 CHECK_WEAK_API_FUNCTION(__sanitizer_set_death_callback);
59 __sanitizer_set_death_callback(StaticDeathCallback);
62 void Fuzzer::PrintUnitInASCII(const Unit &U, const char *PrintAfter) {
63 PrintASCII(U, PrintAfter);
66 void Fuzzer::StaticDeathCallback() {
71 void Fuzzer::DeathCallback() {
73 if (CurrentUnit.size() <= kMaxUnitSizeToPrint) {
74 Print(CurrentUnit, "\n");
75 PrintUnitInASCII(CurrentUnit, "\n");
77 WriteUnitToFileWithPrefix(CurrentUnit, "crash-");
80 void Fuzzer::StaticAlarmCallback() {
85 void Fuzzer::AlarmCallback() {
86 assert(Options.UnitTimeoutSec > 0);
88 duration_cast<seconds>(system_clock::now() - UnitStartTime).count();
89 if (Seconds == 0) return;
90 if (Options.Verbosity >= 2)
91 Printf("AlarmCallback %zd\n", Seconds);
92 if (Seconds >= (size_t)Options.UnitTimeoutSec) {
93 Printf("ALARM: working on the last Unit for %zd seconds\n", Seconds);
94 Printf(" and the timeout value is %d (use -timeout=N to change)\n",
95 Options.UnitTimeoutSec);
96 if (CurrentUnit.size() <= kMaxUnitSizeToPrint) {
97 Print(CurrentUnit, "\n");
98 PrintUnitInASCII(CurrentUnit, "\n");
100 WriteUnitToFileWithPrefix(CurrentUnit, "timeout-");
101 Printf("==%d== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
103 if (__sanitizer_print_stack_trace)
104 __sanitizer_print_stack_trace();
105 Printf("SUMMARY: libFuzzer: timeout\n");
110 void Fuzzer::PrintStats(const char *Where, const char *End) {
111 size_t Seconds = secondsSinceProcessStartUp();
112 size_t ExecPerSec = (Seconds ? TotalNumberOfRuns / Seconds : 0);
114 if (Options.OutputCSV) {
115 static bool csvHeaderPrinted = false;
116 if (!csvHeaderPrinted) {
117 csvHeaderPrinted = true;
118 Printf("runs,block_cov,bits,cc_cov,corpus,execs_per_sec,tbms,reason\n");
120 Printf("%zd,%zd,%zd,%zd,%zd,%zd,%zd,%s\n", TotalNumberOfRuns,
121 LastRecordedBlockCoverage, TotalBits(),
122 LastRecordedCallerCalleeCoverage, Corpus.size(), ExecPerSec,
123 TotalNumberOfExecutedTraceBasedMutations, Where);
126 if (!Options.Verbosity)
128 Printf("#%zd\t%s", TotalNumberOfRuns, Where);
129 if (LastRecordedBlockCoverage)
130 Printf(" cov: %zd", LastRecordedBlockCoverage);
131 if (auto TB = TotalBits())
132 Printf(" bits: %zd", TB);
133 if (LastRecordedCallerCalleeCoverage)
134 Printf(" indir: %zd", LastRecordedCallerCalleeCoverage);
135 Printf(" units: %zd exec/s: %zd", Corpus.size(), ExecPerSec);
136 if (TotalNumberOfExecutedTraceBasedMutations)
137 Printf(" tbm: %zd", TotalNumberOfExecutedTraceBasedMutations);
141 void Fuzzer::RereadOutputCorpus() {
142 if (Options.OutputCorpus.empty()) return;
143 std::vector<Unit> AdditionalCorpus;
144 ReadDirToVectorOfUnits(Options.OutputCorpus.c_str(), &AdditionalCorpus,
145 &EpochOfLastReadOfOutputCorpus);
146 if (Corpus.empty()) {
147 Corpus = AdditionalCorpus;
150 if (!Options.Reload) return;
151 if (Options.Verbosity >= 2)
152 Printf("Reload: read %zd new units.\n", AdditionalCorpus.size());
153 for (auto &X : AdditionalCorpus) {
154 if (X.size() > (size_t)Options.MaxLen)
155 X.resize(Options.MaxLen);
156 if (UnitHashesAddedToCorpus.insert(Hash(X)).second) {
158 CurrentUnit.insert(CurrentUnit.begin(), X.begin(), X.end());
159 if (RunOne(CurrentUnit)) {
161 PrintStats("RELOAD");
167 void Fuzzer::ShuffleAndMinimize() {
168 bool PreferSmall = (Options.PreferSmallDuringInitialShuffle == 1 ||
169 (Options.PreferSmallDuringInitialShuffle == -1 &&
170 USF.GetRand().RandBool()));
171 if (Options.Verbosity)
172 Printf("PreferSmall: %d\n", PreferSmall);
174 std::vector<Unit> NewCorpus;
175 if (Options.ShuffleAtStartUp) {
176 std::random_shuffle(Corpus.begin(), Corpus.end(), USF.GetRand());
179 Corpus.begin(), Corpus.end(),
180 [](const Unit &A, const Unit &B) { return A.size() < B.size(); });
182 Unit &U = CurrentUnit;
183 for (const auto &C : Corpus) {
184 for (size_t First = 0; First < 1; First++) {
186 size_t Last = std::min(First + Options.MaxLen, C.size());
187 U.insert(U.begin(), C.begin() + First, C.begin() + Last);
188 if (Options.OnlyASCII)
191 NewCorpus.push_back(U);
192 if (Options.Verbosity >= 2)
193 Printf("NEW0: %zd L %zd\n", LastRecordedBlockCoverage, U.size());
198 for (auto &X : Corpus)
199 UnitHashesAddedToCorpus.insert(Hash(X));
200 PrintStats("INITED");
203 bool Fuzzer::RunOne(const Unit &U) {
204 UnitStartTime = system_clock::now();
207 PrepareCoverageBeforeRun();
209 bool Res = CheckCoverageAfterRun();
211 auto UnitStopTime = system_clock::now();
213 duration_cast<seconds>(UnitStopTime - UnitStartTime).count();
214 if (!(TotalNumberOfRuns & (TotalNumberOfRuns - 1)) &&
215 secondsSinceProcessStartUp() >= 2)
216 PrintStats("pulse ");
217 if (TimeOfUnit > TimeOfLongestUnitInSeconds &&
218 TimeOfUnit >= Options.ReportSlowUnits) {
219 TimeOfLongestUnitInSeconds = TimeOfUnit;
220 Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
221 WriteUnitToFileWithPrefix(U, "slow-unit-");
226 void Fuzzer::RunOneAndUpdateCorpus(Unit &U) {
227 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
229 if (Options.OnlyASCII)
232 ReportNewCoverage(U);
235 void Fuzzer::ExecuteCallback(const Unit &U) {
236 int Res = USF.TargetFunction(U.data(), U.size());
241 size_t Fuzzer::RecordBlockCoverage() {
242 CHECK_WEAK_API_FUNCTION(__sanitizer_get_total_unique_coverage);
243 return LastRecordedBlockCoverage = __sanitizer_get_total_unique_coverage();
246 size_t Fuzzer::RecordCallerCalleeCoverage() {
247 if (!Options.UseIndirCalls)
249 if (!__sanitizer_get_total_unique_caller_callee_pairs)
251 return LastRecordedCallerCalleeCoverage =
252 __sanitizer_get_total_unique_caller_callee_pairs();
255 void Fuzzer::PrepareCoverageBeforeRun() {
256 if (Options.UseCounters) {
257 size_t NumCounters = __sanitizer_get_number_of_counters();
258 CounterBitmap.resize(NumCounters);
259 __sanitizer_update_counter_bitset_and_clear_counters(0);
261 RecordBlockCoverage();
262 RecordCallerCalleeCoverage();
265 bool Fuzzer::CheckCoverageAfterRun() {
266 size_t OldCoverage = LastRecordedBlockCoverage;
267 size_t NewCoverage = RecordBlockCoverage();
268 size_t OldCallerCalleeCoverage = LastRecordedCallerCalleeCoverage;
269 size_t NewCallerCalleeCoverage = RecordCallerCalleeCoverage();
270 size_t NumNewBits = 0;
271 if (Options.UseCounters)
272 NumNewBits = __sanitizer_update_counter_bitset_and_clear_counters(
273 CounterBitmap.data());
274 return NewCoverage > OldCoverage ||
275 NewCallerCalleeCoverage > OldCallerCalleeCoverage || NumNewBits;
278 void Fuzzer::WriteToOutputCorpus(const Unit &U) {
279 if (Options.OutputCorpus.empty()) return;
280 std::string Path = DirPlusFile(Options.OutputCorpus, Hash(U));
281 WriteToFile(U, Path);
282 if (Options.Verbosity >= 2)
283 Printf("Written to %s\n", Path.c_str());
284 assert(!Options.OnlyASCII || IsASCII(U));
287 void Fuzzer::WriteUnitToFileWithPrefix(const Unit &U, const char *Prefix) {
288 if (!Options.SaveArtifacts)
290 std::string Path = Options.ArtifactPrefix + Prefix + Hash(U);
291 WriteToFile(U, Path);
292 Printf("artifact_prefix='%s'; Test unit written to %s\n",
293 Options.ArtifactPrefix.c_str(), Path.c_str());
294 if (U.size() <= kMaxUnitSizeToPrint) {
296 PrintFileAsBase64(Path);
300 void Fuzzer::SaveCorpus() {
301 if (Options.OutputCorpus.empty()) return;
302 for (const auto &U : Corpus)
303 WriteToFile(U, DirPlusFile(Options.OutputCorpus, Hash(U)));
304 if (Options.Verbosity)
305 Printf("Written corpus of %zd files to %s\n", Corpus.size(),
306 Options.OutputCorpus.c_str());
309 void Fuzzer::PrintStatusForNewUnit(const Unit &U) {
310 if (!Options.PrintNEW)
312 PrintStats("NEW ", "");
313 if (Options.Verbosity) {
314 Printf(" L: %zd", U.size());
317 PrintUnitInASCII(U, "\t");
324 void Fuzzer::ReportNewCoverage(const Unit &U) {
326 UnitHashesAddedToCorpus.insert(Hash(U));
327 PrintStatusForNewUnit(U);
328 WriteToOutputCorpus(U);
329 if (Options.ExitOnFirst)
333 void Fuzzer::Merge(const std::vector<std::string> &Corpora) {
334 if (Corpora.size() <= 1) {
335 Printf("Merge requires two or more corpus dirs\n");
338 auto InitialCorpusDir = Corpora[0];
339 ReadDir(InitialCorpusDir, nullptr);
340 Printf("Merge: running the initial corpus '%s' of %d units\n",
341 InitialCorpusDir.c_str(), Corpus.size());
342 for (auto &U : Corpus)
345 std::vector<std::string> ExtraCorpora(Corpora.begin() + 1, Corpora.end());
348 size_t NumMerged = 0;
349 for (auto &C : ExtraCorpora) {
352 Printf("Merge: merging the extra corpus '%s' of %zd units\n", C.c_str(),
354 for (auto &U : Corpus) {
357 WriteToOutputCorpus(U);
362 Printf("Merge: written %zd out of %zd units\n", NumMerged, NumTried);
365 void Fuzzer::MutateAndTestOne(Unit *U) {
366 for (int i = 0; i < Options.MutateDepth; i++) {
367 StartTraceRecording();
368 size_t Size = U->size();
369 U->resize(Options.MaxLen);
370 size_t NewSize = USF.Mutate(U->data(), Size, U->size());
371 assert(NewSize > 0 && "Mutator returned empty unit");
372 assert(NewSize <= (size_t)Options.MaxLen &&
373 "Mutator return overisized unit");
375 RunOneAndUpdateCorpus(*U);
376 size_t NumTraceBasedMutations = StopTraceRecording();
378 std::min((size_t)Options.TBMWidth, NumTraceBasedMutations);
380 std::min((size_t)Options.TBMDepth, NumTraceBasedMutations);
382 for (size_t w = 0; w < TBMWidth; w++) {
384 for (size_t d = 0; d < TBMDepth; d++) {
385 TotalNumberOfExecutedTraceBasedMutations++;
386 ApplyTraceBasedMutation(USF.GetRand()(NumTraceBasedMutations), U);
387 RunOneAndUpdateCorpus(*U);
393 // Returns an index of random unit from the corpus to mutate.
394 // Hypothesis: units added to the corpus last are more likely to be interesting.
395 // This function gives more wieght to the more recent units.
396 size_t Fuzzer::ChooseUnitIdxToMutate() {
397 size_t N = Corpus.size();
398 size_t Total = (N + 1) * N / 2;
399 size_t R = USF.GetRand()(Total);
400 size_t IdxBeg = 0, IdxEnd = N;
402 while (IdxEnd - IdxBeg >= 2) {
403 size_t Idx = IdxBeg + (IdxEnd - IdxBeg) / 2;
404 if (R > (Idx + 1) * Idx / 2)
413 // Experimental search heuristic: drilling.
414 // - Read, shuffle, execute and minimize the corpus.
415 // - Choose one random unit.
416 // - Reset the coverage.
417 // - Start fuzzing as if the chosen unit was the only element of the corpus.
418 // - When done, reset the coverage again.
419 // - Merge the newly created corpus into the original one.
420 void Fuzzer::Drill() {
421 // The corpus is already read, shuffled, and minimized.
422 assert(!Corpus.empty());
423 Options.PrintNEW = false; // Don't print NEW status lines when drilling.
425 Unit U = ChooseUnitToMutate();
427 CHECK_WEAK_API_FUNCTION(__sanitizer_reset_coverage);
428 __sanitizer_reset_coverage();
430 std::vector<Unit> SavedCorpus;
431 SavedCorpus.swap(Corpus);
433 assert(Corpus.size() == 1);
435 PrintStats("DRILL ");
436 std::string SavedOutputCorpusPath; // Don't write new units while drilling.
437 SavedOutputCorpusPath.swap(Options.OutputCorpus);
440 __sanitizer_reset_coverage();
442 PrintStats("REINIT");
443 SavedOutputCorpusPath.swap(Options.OutputCorpus);
444 for (auto &U : SavedCorpus)
446 PrintStats("MERGE ");
447 Options.PrintNEW = true;
448 size_t NumMerged = 0;
449 for (auto &U : Corpus) {
451 PrintStatusForNewUnit(U);
453 WriteToOutputCorpus(U);
456 PrintStats("MERGED");
457 if (NumMerged && Options.Verbosity)
458 Printf("Drilling discovered %zd new units\n", NumMerged);
461 void Fuzzer::Loop() {
463 size_t J1 = ChooseUnitIdxToMutate();;
465 RereadOutputCorpus();
466 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
468 if (Options.MaxTotalTimeSec > 0 &&
469 secondsSinceProcessStartUp() >
470 static_cast<size_t>(Options.MaxTotalTimeSec))
472 CurrentUnit = Corpus[J1];
473 // Optionally, cross with another unit.
474 if (Options.DoCrossOver && USF.GetRand().RandBool()) {
475 size_t J2 = ChooseUnitIdxToMutate();
476 if (!Corpus[J1].empty() && !Corpus[J2].empty()) {
477 assert(!Corpus[J2].empty());
478 CurrentUnit.resize(Options.MaxLen);
479 size_t NewSize = USF.CrossOver(
480 Corpus[J1].data(), Corpus[J1].size(), Corpus[J2].data(),
481 Corpus[J2].size(), CurrentUnit.data(), CurrentUnit.size());
482 assert(NewSize > 0 && "CrossOver returned empty unit");
483 assert(NewSize <= (size_t)Options.MaxLen &&
484 "CrossOver returned overisized unit");
485 CurrentUnit.resize(NewSize);
488 // Perform several mutations and runs.
489 MutateAndTestOne(&CurrentUnit);
492 PrintStats("DONE ", "\n");
495 void Fuzzer::SyncCorpus() {
496 if (Options.SyncCommand.empty() || Options.OutputCorpus.empty()) return;
497 auto Now = system_clock::now();
498 if (duration_cast<seconds>(Now - LastExternalSync).count() <
501 LastExternalSync = Now;
502 ExecuteCommand(Options.SyncCommand + " " + Options.OutputCorpus);
505 } // namespace fuzzer