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llvm-mirror/lib/Fuzzer/FuzzerLoop.cpp
Ivan Krasin ce1bcd8c31 Use std::piecewise_constant_distribution instead of ad-hoc binary search.
Summary:
Fix the issue with the most recently discovered unit receiving much less attention.

Note: this is the second attempt (prev: r258473). Now, libc++ build is fixed.

Reviewers: aizatsky, kcc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D16487

llvm-svn: 258571
2016-01-22 22:28:27 +00:00

524 lines
16 KiB
C++

//===- FuzzerLoop.cpp - Fuzzer's main loop --------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Fuzzer's main loop.
//===----------------------------------------------------------------------===//
#include "FuzzerInternal.h"
#include <algorithm>
#include <cstring>
#include <memory>
#if defined(__has_include)
#if __has_include(<sanitizer / coverage_interface.h>)
#include <sanitizer/coverage_interface.h>
#endif
#endif
extern "C" {
// Re-declare some of the sanitizer functions as "weak" so that
// libFuzzer can be linked w/o the sanitizers and sanitizer-coverage
// (in which case it will complain at start-up time).
__attribute__((weak)) void __sanitizer_print_stack_trace();
__attribute__((weak)) void __sanitizer_reset_coverage();
__attribute__((weak)) size_t __sanitizer_get_total_unique_caller_callee_pairs();
__attribute__((weak)) size_t __sanitizer_get_total_unique_coverage();
__attribute__((weak)) void
__sanitizer_set_death_callback(void (*callback)(void));
__attribute__((weak)) size_t __sanitizer_get_number_of_counters();
__attribute__((weak)) uintptr_t
__sanitizer_update_counter_bitset_and_clear_counters(uint8_t *bitset);
__attribute__((weak)) uintptr_t
__sanitizer_get_coverage_pc_buffer(uintptr_t **data);
}
namespace fuzzer {
static const size_t kMaxUnitSizeToPrint = 256;
static void MissingWeakApiFunction(const char *FnName) {
Printf("ERROR: %s is not defined. Exiting.\n"
"Did you use -fsanitize-coverage=... to build your code?\n",
FnName);
exit(1);
}
#define CHECK_WEAK_API_FUNCTION(fn) \
do { \
if (!fn) \
MissingWeakApiFunction(#fn); \
} while (false)
// Only one Fuzzer per process.
static Fuzzer *F;
Fuzzer::Fuzzer(UserSuppliedFuzzer &USF, FuzzingOptions Options)
: Generator(USF.GetRand().Rand()), USF(USF), Options(Options) {
SetDeathCallback();
InitializeTraceState();
assert(!F);
F = this;
}
void Fuzzer::SetDeathCallback() {
CHECK_WEAK_API_FUNCTION(__sanitizer_set_death_callback);
__sanitizer_set_death_callback(StaticDeathCallback);
}
void Fuzzer::StaticDeathCallback() {
assert(F);
F->DeathCallback();
}
void Fuzzer::DeathCallback() {
Printf("DEATH:\n");
if (CurrentUnitSize <= kMaxUnitSizeToPrint) {
PrintHexArray(CurrentUnitData, CurrentUnitSize, "\n");
PrintASCII(CurrentUnitData, CurrentUnitSize, "\n");
}
WriteUnitToFileWithPrefix(
{CurrentUnitData, CurrentUnitData + CurrentUnitSize}, "crash-");
}
void Fuzzer::StaticAlarmCallback() {
assert(F);
F->AlarmCallback();
}
void Fuzzer::AlarmCallback() {
assert(Options.UnitTimeoutSec > 0);
size_t Seconds =
duration_cast<seconds>(system_clock::now() - UnitStartTime).count();
if (Seconds == 0)
return;
if (Options.Verbosity >= 2)
Printf("AlarmCallback %zd\n", Seconds);
if (Seconds >= (size_t)Options.UnitTimeoutSec) {
Printf("ALARM: working on the last Unit for %zd seconds\n", Seconds);
Printf(" and the timeout value is %d (use -timeout=N to change)\n",
Options.UnitTimeoutSec);
if (CurrentUnitSize <= kMaxUnitSizeToPrint) {
PrintHexArray(CurrentUnitData, CurrentUnitSize, "\n");
PrintASCII(CurrentUnitData, CurrentUnitSize, "\n");
}
WriteUnitToFileWithPrefix(
{CurrentUnitData, CurrentUnitData + CurrentUnitSize}, "timeout-");
Printf("==%d== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
Seconds);
if (__sanitizer_print_stack_trace)
__sanitizer_print_stack_trace();
Printf("SUMMARY: libFuzzer: timeout\n");
exit(1);
}
}
void Fuzzer::PrintStats(const char *Where, const char *End) {
size_t Seconds = secondsSinceProcessStartUp();
size_t ExecPerSec = (Seconds ? TotalNumberOfRuns / Seconds : 0);
if (Options.OutputCSV) {
static bool csvHeaderPrinted = false;
if (!csvHeaderPrinted) {
csvHeaderPrinted = true;
Printf("runs,block_cov,bits,cc_cov,corpus,execs_per_sec,tbms,reason\n");
}
Printf("%zd,%zd,%zd,%zd,%zd,%zd,%zd,%s\n", TotalNumberOfRuns,
LastRecordedBlockCoverage, TotalBits(),
LastRecordedCallerCalleeCoverage, Corpus.size(), ExecPerSec,
TotalNumberOfExecutedTraceBasedMutations, Where);
}
if (!Options.Verbosity)
return;
Printf("#%zd\t%s", TotalNumberOfRuns, Where);
if (LastRecordedBlockCoverage)
Printf(" cov: %zd", LastRecordedBlockCoverage);
if (auto TB = TotalBits())
Printf(" bits: %zd", TB);
if (LastRecordedCallerCalleeCoverage)
Printf(" indir: %zd", LastRecordedCallerCalleeCoverage);
Printf(" units: %zd exec/s: %zd", Corpus.size(), ExecPerSec);
if (TotalNumberOfExecutedTraceBasedMutations)
Printf(" tbm: %zd", TotalNumberOfExecutedTraceBasedMutations);
Printf("%s", End);
}
void Fuzzer::RereadOutputCorpus() {
if (Options.OutputCorpus.empty())
return;
std::vector<Unit> AdditionalCorpus;
ReadDirToVectorOfUnits(Options.OutputCorpus.c_str(), &AdditionalCorpus,
&EpochOfLastReadOfOutputCorpus);
if (Corpus.empty()) {
Corpus = AdditionalCorpus;
return;
}
if (!Options.Reload)
return;
if (Options.Verbosity >= 2)
Printf("Reload: read %zd new units.\n", AdditionalCorpus.size());
for (auto &X : AdditionalCorpus) {
if (X.size() > (size_t)Options.MaxLen)
X.resize(Options.MaxLen);
if (UnitHashesAddedToCorpus.insert(Hash(X)).second) {
if (RunOne(X)) {
Corpus.push_back(X);
UpdateCorpusDistribution();
PrintStats("RELOAD");
}
}
}
}
void Fuzzer::ShuffleAndMinimize() {
bool PreferSmall = (Options.PreferSmallDuringInitialShuffle == 1 ||
(Options.PreferSmallDuringInitialShuffle == -1 &&
USF.GetRand().RandBool()));
if (Options.Verbosity)
Printf("PreferSmall: %d\n", PreferSmall);
PrintStats("READ ");
std::vector<Unit> NewCorpus;
if (Options.ShuffleAtStartUp) {
std::random_shuffle(Corpus.begin(), Corpus.end(), USF.GetRand());
if (PreferSmall)
std::stable_sort(
Corpus.begin(), Corpus.end(),
[](const Unit &A, const Unit &B) { return A.size() < B.size(); });
}
Unit U;
for (const auto &C : Corpus) {
for (size_t First = 0; First < 1; First++) {
U.clear();
size_t Last = std::min(First + Options.MaxLen, C.size());
U.insert(U.begin(), C.begin() + First, C.begin() + Last);
if (Options.OnlyASCII)
ToASCII(U);
if (RunOne(U)) {
NewCorpus.push_back(U);
if (Options.Verbosity >= 2)
Printf("NEW0: %zd L %zd\n", LastRecordedBlockCoverage, U.size());
}
}
}
Corpus = NewCorpus;
UpdateCorpusDistribution();
for (auto &X : Corpus)
UnitHashesAddedToCorpus.insert(Hash(X));
PrintStats("INITED");
}
bool Fuzzer::RunOne(const Unit &U) {
UnitStartTime = system_clock::now();
TotalNumberOfRuns++;
PrepareCoverageBeforeRun();
ExecuteCallback(U);
bool Res = CheckCoverageAfterRun();
auto UnitStopTime = system_clock::now();
auto TimeOfUnit =
duration_cast<seconds>(UnitStopTime - UnitStartTime).count();
if (!(TotalNumberOfRuns & (TotalNumberOfRuns - 1)) &&
secondsSinceProcessStartUp() >= 2)
PrintStats("pulse ");
if (TimeOfUnit > TimeOfLongestUnitInSeconds &&
TimeOfUnit >= Options.ReportSlowUnits) {
TimeOfLongestUnitInSeconds = TimeOfUnit;
Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
WriteUnitToFileWithPrefix(U, "slow-unit-");
}
return Res;
}
void Fuzzer::RunOneAndUpdateCorpus(Unit &U) {
if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
return;
if (Options.OnlyASCII)
ToASCII(U);
if (RunOne(U))
ReportNewCoverage(U);
}
void Fuzzer::ExecuteCallback(const Unit &U) {
// We copy the contents of Unit into a separate heap buffer
// so that we reliably find buffer overflows in it.
std::unique_ptr<uint8_t[]> Data(new uint8_t[U.size()]);
memcpy(Data.get(), U.data(), U.size());
AssignTaintLabels(Data.get(), U.size());
CurrentUnitData = Data.get();
CurrentUnitSize = U.size();
int Res = USF.TargetFunction(Data.get(), U.size());
(void)Res;
assert(Res == 0);
CurrentUnitData = nullptr;
CurrentUnitSize = 0;
}
size_t Fuzzer::RecordBlockCoverage() {
CHECK_WEAK_API_FUNCTION(__sanitizer_get_total_unique_coverage);
uintptr_t PrevCoverage = LastRecordedBlockCoverage;
LastRecordedBlockCoverage = __sanitizer_get_total_unique_coverage();
if (PrevCoverage == LastRecordedBlockCoverage || !Options.PrintNewCovPcs)
return LastRecordedBlockCoverage;
uintptr_t PrevBufferLen = LastCoveragePcBufferLen;
uintptr_t *CoverageBuf;
LastCoveragePcBufferLen = __sanitizer_get_coverage_pc_buffer(&CoverageBuf);
assert(CoverageBuf);
for (size_t i = PrevBufferLen; i < LastCoveragePcBufferLen; ++i) {
Printf("%p\n", CoverageBuf[i]);
}
return LastRecordedBlockCoverage;
}
size_t Fuzzer::RecordCallerCalleeCoverage() {
if (!Options.UseIndirCalls)
return 0;
if (!__sanitizer_get_total_unique_caller_callee_pairs)
return 0;
return LastRecordedCallerCalleeCoverage =
__sanitizer_get_total_unique_caller_callee_pairs();
}
void Fuzzer::PrepareCoverageBeforeRun() {
if (Options.UseCounters) {
size_t NumCounters = __sanitizer_get_number_of_counters();
CounterBitmap.resize(NumCounters);
__sanitizer_update_counter_bitset_and_clear_counters(0);
}
RecordBlockCoverage();
RecordCallerCalleeCoverage();
}
bool Fuzzer::CheckCoverageAfterRun() {
size_t OldCoverage = LastRecordedBlockCoverage;
size_t NewCoverage = RecordBlockCoverage();
size_t OldCallerCalleeCoverage = LastRecordedCallerCalleeCoverage;
size_t NewCallerCalleeCoverage = RecordCallerCalleeCoverage();
size_t NumNewBits = 0;
if (Options.UseCounters)
NumNewBits = __sanitizer_update_counter_bitset_and_clear_counters(
CounterBitmap.data());
return NewCoverage > OldCoverage ||
NewCallerCalleeCoverage > OldCallerCalleeCoverage || NumNewBits;
}
void Fuzzer::WriteToOutputCorpus(const Unit &U) {
if (Options.OutputCorpus.empty())
return;
std::string Path = DirPlusFile(Options.OutputCorpus, Hash(U));
WriteToFile(U, Path);
if (Options.Verbosity >= 2)
Printf("Written to %s\n", Path.c_str());
assert(!Options.OnlyASCII || IsASCII(U));
}
void Fuzzer::WriteUnitToFileWithPrefix(const Unit &U, const char *Prefix) {
if (!Options.SaveArtifacts)
return;
std::string Path = Options.ArtifactPrefix + Prefix + Hash(U);
if (!Options.ExactArtifactPath.empty())
Path = Options.ExactArtifactPath; // Overrides ArtifactPrefix.
WriteToFile(U, Path);
Printf("artifact_prefix='%s'; Test unit written to %s\n",
Options.ArtifactPrefix.c_str(), Path.c_str());
if (U.size() <= kMaxUnitSizeToPrint)
Printf("Base64: %s\n", Base64(U).c_str());
}
void Fuzzer::SaveCorpus() {
if (Options.OutputCorpus.empty())
return;
for (const auto &U : Corpus)
WriteToFile(U, DirPlusFile(Options.OutputCorpus, Hash(U)));
if (Options.Verbosity)
Printf("Written corpus of %zd files to %s\n", Corpus.size(),
Options.OutputCorpus.c_str());
}
void Fuzzer::PrintStatusForNewUnit(const Unit &U) {
if (!Options.PrintNEW)
return;
PrintStats("NEW ", "");
if (Options.Verbosity) {
Printf(" L: %zd ", U.size());
USF.GetMD().PrintMutationSequence();
Printf("\n");
}
}
void Fuzzer::ReportNewCoverage(const Unit &U) {
Corpus.push_back(U);
UpdateCorpusDistribution();
UnitHashesAddedToCorpus.insert(Hash(U));
USF.GetMD().RecordSuccessfulMutationSequence();
PrintStatusForNewUnit(U);
WriteToOutputCorpus(U);
if (Options.ExitOnFirst)
exit(0);
}
void Fuzzer::Merge(const std::vector<std::string> &Corpora) {
if (Corpora.size() <= 1) {
Printf("Merge requires two or more corpus dirs\n");
return;
}
auto InitialCorpusDir = Corpora[0];
ReadDir(InitialCorpusDir, nullptr);
Printf("Merge: running the initial corpus '%s' of %d units\n",
InitialCorpusDir.c_str(), Corpus.size());
for (auto &U : Corpus)
RunOne(U);
std::vector<std::string> ExtraCorpora(Corpora.begin() + 1, Corpora.end());
size_t NumTried = 0;
size_t NumMerged = 0;
for (auto &C : ExtraCorpora) {
Corpus.clear();
ReadDir(C, nullptr);
Printf("Merge: merging the extra corpus '%s' of %zd units\n", C.c_str(),
Corpus.size());
for (auto &U : Corpus) {
NumTried++;
if (RunOne(U)) {
WriteToOutputCorpus(U);
NumMerged++;
}
}
}
Printf("Merge: written %zd out of %zd units\n", NumMerged, NumTried);
}
void Fuzzer::MutateAndTestOne() {
USF.GetMD().StartMutationSequence();
auto U = ChooseUnitToMutate();
for (int i = 0; i < Options.MutateDepth; i++) {
size_t Size = U.size();
U.resize(Options.MaxLen);
size_t NewSize = USF.Mutate(U.data(), Size, U.size());
assert(NewSize > 0 && "Mutator returned empty unit");
assert(NewSize <= (size_t)Options.MaxLen &&
"Mutator return overisized unit");
U.resize(NewSize);
if (i == 0)
StartTraceRecording();
RunOneAndUpdateCorpus(U);
StopTraceRecording();
}
}
// Returns an index of random unit from the corpus to mutate.
// Hypothesis: units added to the corpus last are more likely to be interesting.
// This function gives more weight to the more recent units.
size_t Fuzzer::ChooseUnitIdxToMutate() {
size_t Idx = static_cast<size_t>(CorpusDistribution(Generator));
assert(Idx < Corpus.size());
return Idx;
}
// Experimental search heuristic: drilling.
// - Read, shuffle, execute and minimize the corpus.
// - Choose one random unit.
// - Reset the coverage.
// - Start fuzzing as if the chosen unit was the only element of the corpus.
// - When done, reset the coverage again.
// - Merge the newly created corpus into the original one.
void Fuzzer::Drill() {
// The corpus is already read, shuffled, and minimized.
assert(!Corpus.empty());
Options.PrintNEW = false; // Don't print NEW status lines when drilling.
Unit U = ChooseUnitToMutate();
CHECK_WEAK_API_FUNCTION(__sanitizer_reset_coverage);
__sanitizer_reset_coverage();
std::vector<Unit> SavedCorpus;
SavedCorpus.swap(Corpus);
Corpus.push_back(U);
UpdateCorpusDistribution();
assert(Corpus.size() == 1);
RunOne(U);
PrintStats("DRILL ");
std::string SavedOutputCorpusPath; // Don't write new units while drilling.
SavedOutputCorpusPath.swap(Options.OutputCorpus);
Loop();
__sanitizer_reset_coverage();
PrintStats("REINIT");
SavedOutputCorpusPath.swap(Options.OutputCorpus);
for (auto &U : SavedCorpus)
RunOne(U);
PrintStats("MERGE ");
Options.PrintNEW = true;
size_t NumMerged = 0;
for (auto &U : Corpus) {
if (RunOne(U)) {
PrintStatusForNewUnit(U);
NumMerged++;
WriteToOutputCorpus(U);
}
}
PrintStats("MERGED");
if (NumMerged && Options.Verbosity)
Printf("Drilling discovered %zd new units\n", NumMerged);
}
void Fuzzer::Loop() {
system_clock::time_point LastCorpusReload = system_clock::now();
if (Options.DoCrossOver)
USF.GetMD().SetCorpus(&Corpus);
while (true) {
SyncCorpus();
auto Now = system_clock::now();
if (duration_cast<seconds>(Now - LastCorpusReload).count()) {
RereadOutputCorpus();
LastCorpusReload = Now;
}
if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
break;
if (Options.MaxTotalTimeSec > 0 &&
secondsSinceProcessStartUp() >
static_cast<size_t>(Options.MaxTotalTimeSec))
break;
// Perform several mutations and runs.
MutateAndTestOne();
}
PrintStats("DONE ", "\n");
USF.GetMD().PrintRecommendedDictionary();
}
void Fuzzer::SyncCorpus() {
if (Options.SyncCommand.empty() || Options.OutputCorpus.empty())
return;
auto Now = system_clock::now();
if (duration_cast<seconds>(Now - LastExternalSync).count() <
Options.SyncTimeout)
return;
LastExternalSync = Now;
ExecuteCommand(Options.SyncCommand + " " + Options.OutputCorpus);
}
void Fuzzer::UpdateCorpusDistribution() {
size_t N = Corpus.size();
std::vector<double> Intervals(N + 1);
std::vector<double> Weights(N);
std::iota(Intervals.begin(), Intervals.end(), 0);
std::iota(Weights.begin(), Weights.end(), 1);
CorpusDistribution = std::piecewise_constant_distribution<double>(
Intervals.begin(), Intervals.end(), Weights.begin());
}
} // namespace fuzzer