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 if (!Options.Verbosity) return;
112 size_t Seconds = secondsSinceProcessStartUp();
113 size_t ExecPerSec = (Seconds ? TotalNumberOfRuns / Seconds : 0);
114 Printf("#%zd\t%s", TotalNumberOfRuns, Where);
115 if (LastRecordedBlockCoverage)
116 Printf(" cov: %zd", LastRecordedBlockCoverage);
117 if (auto TB = TotalBits())
118 Printf(" bits: %zd", TB);
119 if (LastRecordedCallerCalleeCoverage)
120 Printf(" indir: %zd", LastRecordedCallerCalleeCoverage);
121 Printf(" units: %zd exec/s: %zd", Corpus.size(), ExecPerSec);
122 if (TotalNumberOfExecutedTraceBasedMutations)
123 Printf(" tbm: %zd", TotalNumberOfExecutedTraceBasedMutations);
127 void Fuzzer::RereadOutputCorpus() {
128 if (Options.OutputCorpus.empty()) return;
129 std::vector<Unit> AdditionalCorpus;
130 ReadDirToVectorOfUnits(Options.OutputCorpus.c_str(), &AdditionalCorpus,
131 &EpochOfLastReadOfOutputCorpus);
132 if (Corpus.empty()) {
133 Corpus = AdditionalCorpus;
136 if (!Options.Reload) return;
137 if (Options.Verbosity >= 2)
138 Printf("Reload: read %zd new units.\n", AdditionalCorpus.size());
139 for (auto &X : AdditionalCorpus) {
140 if (X.size() > (size_t)Options.MaxLen)
141 X.resize(Options.MaxLen);
142 if (UnitHashesAddedToCorpus.insert(Hash(X)).second) {
144 CurrentUnit.insert(CurrentUnit.begin(), X.begin(), X.end());
145 if (RunOne(CurrentUnit)) {
147 if (Options.Verbosity >= 1)
148 PrintStats("RELOAD");
154 void Fuzzer::ShuffleAndMinimize() {
155 bool PreferSmall = (Options.PreferSmallDuringInitialShuffle == 1 ||
156 (Options.PreferSmallDuringInitialShuffle == -1 &&
157 USF.GetRand().RandBool()));
158 if (Options.Verbosity)
159 Printf("PreferSmall: %d\n", PreferSmall);
161 std::vector<Unit> NewCorpus;
162 if (Options.ShuffleAtStartUp) {
163 std::random_shuffle(Corpus.begin(), Corpus.end(), USF.GetRand());
166 Corpus.begin(), Corpus.end(),
167 [](const Unit &A, const Unit &B) { return A.size() < B.size(); });
169 Unit &U = CurrentUnit;
170 for (const auto &C : Corpus) {
171 for (size_t First = 0; First < 1; First++) {
173 size_t Last = std::min(First + Options.MaxLen, C.size());
174 U.insert(U.begin(), C.begin() + First, C.begin() + Last);
175 if (Options.OnlyASCII)
178 NewCorpus.push_back(U);
179 if (Options.Verbosity >= 2)
180 Printf("NEW0: %zd L %zd\n", LastRecordedBlockCoverage, U.size());
185 for (auto &X : Corpus)
186 UnitHashesAddedToCorpus.insert(Hash(X));
187 PrintStats("INITED");
190 bool Fuzzer::RunOne(const Unit &U) {
191 UnitStartTime = system_clock::now();
194 PrepareCoverageBeforeRun();
196 bool Res = CheckCoverageAfterRun();
198 auto UnitStopTime = system_clock::now();
200 duration_cast<seconds>(UnitStopTime - UnitStartTime).count();
201 if (!(TotalNumberOfRuns & (TotalNumberOfRuns - 1))
202 && secondsSinceProcessStartUp() >= 2
203 && Options.Verbosity)
204 PrintStats("pulse ");
205 if (TimeOfUnit > TimeOfLongestUnitInSeconds &&
206 TimeOfUnit >= Options.ReportSlowUnits) {
207 TimeOfLongestUnitInSeconds = TimeOfUnit;
208 Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
209 WriteUnitToFileWithPrefix(U, "slow-unit-");
214 void Fuzzer::RunOneAndUpdateCorpus(Unit &U) {
215 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
217 if (Options.OnlyASCII)
220 ReportNewCoverage(U);
223 void Fuzzer::ExecuteCallback(const Unit &U) {
224 int Res = USF.TargetFunction(U.data(), U.size());
229 size_t Fuzzer::RecordBlockCoverage() {
230 CHECK_WEAK_API_FUNCTION(__sanitizer_get_total_unique_coverage);
231 return LastRecordedBlockCoverage = __sanitizer_get_total_unique_coverage();
234 size_t Fuzzer::RecordCallerCalleeCoverage() {
235 if (!Options.UseIndirCalls)
237 if (!__sanitizer_get_total_unique_caller_callee_pairs)
239 return LastRecordedCallerCalleeCoverage =
240 __sanitizer_get_total_unique_caller_callee_pairs();
243 void Fuzzer::PrepareCoverageBeforeRun() {
244 if (Options.UseCounters) {
245 size_t NumCounters = __sanitizer_get_number_of_counters();
246 CounterBitmap.resize(NumCounters);
247 __sanitizer_update_counter_bitset_and_clear_counters(0);
249 RecordBlockCoverage();
250 RecordCallerCalleeCoverage();
253 bool Fuzzer::CheckCoverageAfterRun() {
254 size_t OldCoverage = LastRecordedBlockCoverage;
255 size_t NewCoverage = RecordBlockCoverage();
256 size_t OldCallerCalleeCoverage = LastRecordedCallerCalleeCoverage;
257 size_t NewCallerCalleeCoverage = RecordCallerCalleeCoverage();
258 size_t NumNewBits = 0;
259 if (Options.UseCounters)
260 NumNewBits = __sanitizer_update_counter_bitset_and_clear_counters(
261 CounterBitmap.data());
262 return NewCoverage > OldCoverage ||
263 NewCallerCalleeCoverage > OldCallerCalleeCoverage || NumNewBits;
266 void Fuzzer::WriteToOutputCorpus(const Unit &U) {
267 if (Options.OutputCorpus.empty()) return;
268 std::string Path = DirPlusFile(Options.OutputCorpus, Hash(U));
269 WriteToFile(U, Path);
270 if (Options.Verbosity >= 2)
271 Printf("Written to %s\n", Path.c_str());
272 assert(!Options.OnlyASCII || IsASCII(U));
275 void Fuzzer::WriteUnitToFileWithPrefix(const Unit &U, const char *Prefix) {
276 if (!Options.SaveArtifacts)
278 std::string Path = Options.ArtifactPrefix + Prefix + Hash(U);
279 WriteToFile(U, Path);
280 Printf("artifact_prefix='%s'; Test unit written to %s\n",
281 Options.ArtifactPrefix.c_str(), Path.c_str());
282 if (U.size() <= kMaxUnitSizeToPrint) {
284 PrintFileAsBase64(Path);
288 void Fuzzer::SaveCorpus() {
289 if (Options.OutputCorpus.empty()) return;
290 for (const auto &U : Corpus)
291 WriteToFile(U, DirPlusFile(Options.OutputCorpus, Hash(U)));
292 if (Options.Verbosity)
293 Printf("Written corpus of %zd files to %s\n", Corpus.size(),
294 Options.OutputCorpus.c_str());
297 void Fuzzer::PrintStatusForNewUnit(const Unit &U) {
298 if (!Options.PrintNEW)
300 PrintStats("NEW ", "");
301 if (Options.Verbosity) {
302 Printf(" L: %zd", U.size());
305 PrintUnitInASCII(U, "\t");
312 void Fuzzer::ReportNewCoverage(const Unit &U) {
314 UnitHashesAddedToCorpus.insert(Hash(U));
315 PrintStatusForNewUnit(U);
316 WriteToOutputCorpus(U);
317 if (Options.ExitOnFirst)
321 void Fuzzer::Merge(const std::vector<std::string> &Corpora) {
322 if (Corpora.size() <= 1) {
323 Printf("Merge requires two or more corpus dirs\n");
326 auto InitialCorpusDir = Corpora[0];
327 ReadDir(InitialCorpusDir, nullptr);
328 Printf("Merge: running the initial corpus '%s' of %d units\n",
329 InitialCorpusDir.c_str(), Corpus.size());
330 for (auto &U : Corpus)
333 std::vector<std::string> ExtraCorpora(Corpora.begin() + 1, Corpora.end());
336 size_t NumMerged = 0;
337 for (auto &C : ExtraCorpora) {
340 Printf("Merge: merging the extra corpus '%s' of %zd units\n", C.c_str(),
342 for (auto &U : Corpus) {
345 WriteToOutputCorpus(U);
350 Printf("Merge: written %zd out of %zd units\n", NumMerged, NumTried);
353 void Fuzzer::MutateAndTestOne(Unit *U) {
354 for (int i = 0; i < Options.MutateDepth; i++) {
355 StartTraceRecording();
356 size_t Size = U->size();
357 U->resize(Options.MaxLen);
358 size_t NewSize = USF.Mutate(U->data(), Size, U->size());
359 assert(NewSize > 0 && "Mutator returned empty unit");
360 assert(NewSize <= (size_t)Options.MaxLen &&
361 "Mutator return overisized unit");
363 RunOneAndUpdateCorpus(*U);
364 size_t NumTraceBasedMutations = StopTraceRecording();
366 std::min((size_t)Options.TBMWidth, NumTraceBasedMutations);
368 std::min((size_t)Options.TBMDepth, NumTraceBasedMutations);
370 for (size_t w = 0; w < TBMWidth; w++) {
372 for (size_t d = 0; d < TBMDepth; d++) {
373 TotalNumberOfExecutedTraceBasedMutations++;
374 ApplyTraceBasedMutation(USF.GetRand()(NumTraceBasedMutations), U);
375 RunOneAndUpdateCorpus(*U);
381 // Returns an index of random unit from the corpus to mutate.
382 // Hypothesis: units added to the corpus last are more likely to be interesting.
383 // This function gives more wieght to the more recent units.
384 size_t Fuzzer::ChooseUnitIdxToMutate() {
385 size_t N = Corpus.size();
386 size_t Total = (N + 1) * N / 2;
387 size_t R = USF.GetRand()(Total);
388 size_t IdxBeg = 0, IdxEnd = N;
390 while (IdxEnd - IdxBeg >= 2) {
391 size_t Idx = IdxBeg + (IdxEnd - IdxBeg) / 2;
392 if (R > (Idx + 1) * Idx / 2)
401 // Experimental search heuristic: drilling.
402 // - Read, shuffle, execute and minimize the corpus.
403 // - Choose one random unit.
404 // - Reset the coverage.
405 // - Start fuzzing as if the chosen unit was the only element of the corpus.
406 // - When done, reset the coverage again.
407 // - Merge the newly created corpus into the original one.
408 void Fuzzer::Drill() {
409 // The corpus is already read, shuffled, and minimized.
410 assert(!Corpus.empty());
411 Options.PrintNEW = false; // Don't print NEW status lines when drilling.
413 Unit U = ChooseUnitToMutate();
415 CHECK_WEAK_API_FUNCTION(__sanitizer_reset_coverage);
416 __sanitizer_reset_coverage();
418 std::vector<Unit> SavedCorpus;
419 SavedCorpus.swap(Corpus);
421 assert(Corpus.size() == 1);
423 PrintStats("DRILL ");
424 std::string SavedOutputCorpusPath; // Don't write new units while drilling.
425 SavedOutputCorpusPath.swap(Options.OutputCorpus);
428 __sanitizer_reset_coverage();
430 PrintStats("REINIT");
431 SavedOutputCorpusPath.swap(Options.OutputCorpus);
432 for (auto &U : SavedCorpus)
434 PrintStats("MERGE ");
435 Options.PrintNEW = true;
436 size_t NumMerged = 0;
437 for (auto &U : Corpus) {
439 PrintStatusForNewUnit(U);
441 WriteToOutputCorpus(U);
444 PrintStats("MERGED");
445 if (NumMerged && Options.Verbosity)
446 Printf("Drilling discovered %zd new units\n", NumMerged);
449 void Fuzzer::Loop() {
451 size_t J1 = ChooseUnitIdxToMutate();;
453 RereadOutputCorpus();
454 if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
456 if (Options.MaxTotalTimeSec > 0 &&
457 secondsSinceProcessStartUp() >
458 static_cast<size_t>(Options.MaxTotalTimeSec))
460 CurrentUnit = Corpus[J1];
461 // Optionally, cross with another unit.
462 if (Options.DoCrossOver && USF.GetRand().RandBool()) {
463 size_t J2 = ChooseUnitIdxToMutate();
464 if (!Corpus[J1].empty() && !Corpus[J2].empty()) {
465 assert(!Corpus[J2].empty());
466 CurrentUnit.resize(Options.MaxLen);
467 size_t NewSize = USF.CrossOver(
468 Corpus[J1].data(), Corpus[J1].size(), Corpus[J2].data(),
469 Corpus[J2].size(), CurrentUnit.data(), CurrentUnit.size());
470 assert(NewSize > 0 && "CrossOver returned empty unit");
471 assert(NewSize <= (size_t)Options.MaxLen &&
472 "CrossOver returned overisized unit");
473 CurrentUnit.resize(NewSize);
476 // Perform several mutations and runs.
477 MutateAndTestOne(&CurrentUnit);
481 void Fuzzer::SyncCorpus() {
482 if (Options.SyncCommand.empty() || Options.OutputCorpus.empty()) return;
483 auto Now = system_clock::now();
484 if (duration_cast<seconds>(Now - LastExternalSync).count() <
487 LastExternalSync = Now;
488 ExecuteCommand(Options.SyncCommand + " " + Options.OutputCorpus);
491 } // namespace fuzzer