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llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp

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//===- FuzzerLoop.cpp - Fuzzer's main loop --------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Fuzzer's main loop.
//===----------------------------------------------------------------------===//
#include "FuzzerCorpus.h"
#include "FuzzerIO.h"
#include "FuzzerInternal.h"
#include "FuzzerMutate.h"
#include "FuzzerPlatform.h"
#include "FuzzerRandom.h"
#include "FuzzerTracePC.h"
#include <algorithm>
#include <cstring>
#include <memory>
#include <mutex>
#include <set>
#if defined(__has_include)
#if __has_include(<sanitizer / lsan_interface.h>)
#include <sanitizer/lsan_interface.h>
#endif
#endif
#define NO_SANITIZE_MEMORY
#if defined(__has_feature)
#if __has_feature(memory_sanitizer)
#undef NO_SANITIZE_MEMORY
#define NO_SANITIZE_MEMORY __attribute__((no_sanitize_memory))
#endif
#endif
namespace fuzzer {
static const size_t kMaxUnitSizeToPrint = 256;
thread_local bool Fuzzer::IsMyThread;
bool RunningUserCallback = false;
// Only one Fuzzer per process.
static Fuzzer *F;
// Leak detection is expensive, so we first check if there were more mallocs
// than frees (using the sanitizer malloc hooks) and only then try to call lsan.
struct MallocFreeTracer {
void Start(int TraceLevel) {
this->TraceLevel = TraceLevel;
if (TraceLevel)
Printf("MallocFreeTracer: START\n");
Mallocs = 0;
Frees = 0;
}
// Returns true if there were more mallocs than frees.
bool Stop() {
if (TraceLevel)
Printf("MallocFreeTracer: STOP %zd %zd (%s)\n", Mallocs.load(),
Frees.load(), Mallocs == Frees ? "same" : "DIFFERENT");
bool Result = Mallocs > Frees;
Mallocs = 0;
Frees = 0;
TraceLevel = 0;
return Result;
}
std::atomic<size_t> Mallocs;
std::atomic<size_t> Frees;
int TraceLevel = 0;
std::recursive_mutex TraceMutex;
bool TraceDisabled = false;
};
static MallocFreeTracer AllocTracer;
// Locks printing and avoids nested hooks triggered from mallocs/frees in
// sanitizer.
class TraceLock {
public:
TraceLock() : Lock(AllocTracer.TraceMutex) {
AllocTracer.TraceDisabled = !AllocTracer.TraceDisabled;
}
~TraceLock() { AllocTracer.TraceDisabled = !AllocTracer.TraceDisabled; }
bool IsDisabled() const {
// This is already inverted value.
return !AllocTracer.TraceDisabled;
}
private:
std::lock_guard<std::recursive_mutex> Lock;
};
ATTRIBUTE_NO_SANITIZE_MEMORY
void MallocHook(const volatile void *ptr, size_t size) {
size_t N = AllocTracer.Mallocs++;
F->HandleMalloc(size);
if (int TraceLevel = AllocTracer.TraceLevel) {
TraceLock Lock;
if (Lock.IsDisabled())
return;
Printf("MALLOC[%zd] %p %zd\n", N, ptr, size);
if (TraceLevel >= 2 && EF)
PrintStackTrace();
}
}
ATTRIBUTE_NO_SANITIZE_MEMORY
void FreeHook(const volatile void *ptr) {
size_t N = AllocTracer.Frees++;
if (int TraceLevel = AllocTracer.TraceLevel) {
TraceLock Lock;
if (Lock.IsDisabled())
return;
Printf("FREE[%zd] %p\n", N, ptr);
if (TraceLevel >= 2 && EF)
PrintStackTrace();
}
}
// Crash on a single malloc that exceeds the rss limit.
void Fuzzer::HandleMalloc(size_t Size) {
if (!Options.MallocLimitMb || (Size >> 20) < (size_t)Options.MallocLimitMb)
return;
Printf("==%d== ERROR: libFuzzer: out-of-memory (malloc(%zd))\n", GetPid(),
Size);
Printf(" To change the out-of-memory limit use -rss_limit_mb=<N>\n\n");
PrintStackTrace();
DumpCurrentUnit("oom-");
Printf("SUMMARY: libFuzzer: out-of-memory\n");
PrintFinalStats();
_Exit(Options.OOMExitCode); // Stop right now.
}
Fuzzer::Fuzzer(UserCallback CB, InputCorpus &Corpus, MutationDispatcher &MD,
FuzzingOptions Options)
: CB(CB), Corpus(Corpus), MD(MD), Options(Options) {
if (EF->__sanitizer_set_death_callback)
EF->__sanitizer_set_death_callback(StaticDeathCallback);
assert(!F);
F = this;
TPC.ResetMaps();
IsMyThread = true;
if (Options.DetectLeaks && EF->__sanitizer_install_malloc_and_free_hooks)
EF->__sanitizer_install_malloc_and_free_hooks(MallocHook, FreeHook);
TPC.SetUseCounters(Options.UseCounters);
TPC.SetUseValueProfileMask(Options.UseValueProfile);
if (Options.Verbosity)
TPC.PrintModuleInfo();
if (!Options.OutputCorpus.empty() && Options.ReloadIntervalSec)
EpochOfLastReadOfOutputCorpus = GetEpoch(Options.OutputCorpus);
MaxInputLen = MaxMutationLen = Options.MaxLen;
TmpMaxMutationLen = 0; // Will be set once we load the corpus.
AllocateCurrentUnitData();
CurrentUnitSize = 0;
memset(BaseSha1, 0, sizeof(BaseSha1));
}
Fuzzer::~Fuzzer() {}
void Fuzzer::AllocateCurrentUnitData() {
if (CurrentUnitData || MaxInputLen == 0)
return;
CurrentUnitData = new uint8_t[MaxInputLen];
}
void Fuzzer::StaticDeathCallback() {
assert(F);
F->DeathCallback();
}
void Fuzzer::DumpCurrentUnit(const char *Prefix) {
if (!CurrentUnitData)
return; // Happens when running individual inputs.
ScopedDisableMsanInterceptorChecks S;
MD.PrintMutationSequence();
Printf("; base unit: %s\n", Sha1ToString(BaseSha1).c_str());
size_t UnitSize = CurrentUnitSize;
if (UnitSize <= kMaxUnitSizeToPrint) {
PrintHexArray(CurrentUnitData, UnitSize, "\n");
PrintASCII(CurrentUnitData, UnitSize, "\n");
}
WriteUnitToFileWithPrefix({CurrentUnitData, CurrentUnitData + UnitSize},
Prefix);
}
NO_SANITIZE_MEMORY
void Fuzzer::DeathCallback() {
DumpCurrentUnit("crash-");
PrintFinalStats();
}
void Fuzzer::StaticAlarmCallback() {
assert(F);
F->AlarmCallback();
}
void Fuzzer::StaticCrashSignalCallback() {
assert(F);
F->CrashCallback();
}
void Fuzzer::StaticExitCallback() {
assert(F);
F->ExitCallback();
}
void Fuzzer::StaticInterruptCallback() {
assert(F);
F->InterruptCallback();
}
void Fuzzer::StaticGracefulExitCallback() {
assert(F);
F->GracefulExitRequested = true;
Printf("INFO: signal received, trying to exit gracefully\n");
}
void Fuzzer::StaticFileSizeExceedCallback() {
Printf("==%lu== ERROR: libFuzzer: file size exceeded\n", GetPid());
exit(1);
}
void Fuzzer::CrashCallback() {
if (EF->__sanitizer_acquire_crash_state &&
!EF->__sanitizer_acquire_crash_state())
return;
Printf("==%lu== ERROR: libFuzzer: deadly signal\n", GetPid());
PrintStackTrace();
Printf("NOTE: libFuzzer has rudimentary signal handlers.\n"
" Combine libFuzzer with AddressSanitizer or similar for better "
"crash reports.\n");
Printf("SUMMARY: libFuzzer: deadly signal\n");
DumpCurrentUnit("crash-");
PrintFinalStats();
_Exit(Options.ErrorExitCode); // Stop right now.
}
void Fuzzer::ExitCallback() {
if (!RunningUserCallback)
return; // This exit did not come from the user callback
if (EF->__sanitizer_acquire_crash_state &&
!EF->__sanitizer_acquire_crash_state())
return;
Printf("==%lu== ERROR: libFuzzer: fuzz target exited\n", GetPid());
PrintStackTrace();
Printf("SUMMARY: libFuzzer: fuzz target exited\n");
DumpCurrentUnit("crash-");
PrintFinalStats();
_Exit(Options.ErrorExitCode);
}
void Fuzzer::MaybeExitGracefully() {
if (!F->GracefulExitRequested) return;
Printf("==%lu== INFO: libFuzzer: exiting as requested\n", GetPid());
RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
F->PrintFinalStats();
_Exit(0);
}
void Fuzzer::InterruptCallback() {
Printf("==%lu== libFuzzer: run interrupted; exiting\n", GetPid());
PrintFinalStats();
ScopedDisableMsanInterceptorChecks S; // RmDirRecursive may call opendir().
RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
// Stop right now, don't perform any at-exit actions.
_Exit(Options.InterruptExitCode);
}
NO_SANITIZE_MEMORY
void Fuzzer::AlarmCallback() {
assert(Options.UnitTimeoutSec > 0);
// In Windows and Fuchsia, Alarm callback is executed by a different thread.
// NetBSD's current behavior needs this change too.
#if !LIBFUZZER_WINDOWS && !LIBFUZZER_NETBSD && !LIBFUZZER_FUCHSIA
if (!InFuzzingThread())
return;
#endif
if (!RunningUserCallback)
return; // We have not started running units yet.
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) {
if (EF->__sanitizer_acquire_crash_state &&
!EF->__sanitizer_acquire_crash_state())
return;
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);
DumpCurrentUnit("timeout-");
Printf("==%lu== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
Seconds);
PrintStackTrace();
Printf("SUMMARY: libFuzzer: timeout\n");
PrintFinalStats();
_Exit(Options.TimeoutExitCode); // Stop right now.
}
}
void Fuzzer::RssLimitCallback() {
if (EF->__sanitizer_acquire_crash_state &&
!EF->__sanitizer_acquire_crash_state())
return;
Printf(
"==%lu== ERROR: libFuzzer: out-of-memory (used: %zdMb; limit: %zdMb)\n",
GetPid(), GetPeakRSSMb(), Options.RssLimitMb);
Printf(" To change the out-of-memory limit use -rss_limit_mb=<N>\n\n");
PrintMemoryProfile();
DumpCurrentUnit("oom-");
Printf("SUMMARY: libFuzzer: out-of-memory\n");
PrintFinalStats();
_Exit(Options.OOMExitCode); // Stop right now.
}
void Fuzzer::PrintStats(const char *Where, const char *End, size_t Units,
size_t Features) {
size_t ExecPerSec = execPerSec();
if (!Options.Verbosity)
return;
Printf("#%zd\t%s", TotalNumberOfRuns, Where);
if (size_t N = TPC.GetTotalPCCoverage())
Printf(" cov: %zd", N);
if (size_t N = Features ? Features : Corpus.NumFeatures())
Printf(" ft: %zd", N);
if (!Corpus.empty()) {
Printf(" corp: %zd", Corpus.NumActiveUnits());
if (size_t N = Corpus.SizeInBytes()) {
if (N < (1 << 14))
Printf("/%zdb", N);
else if (N < (1 << 24))
Printf("/%zdKb", N >> 10);
else
Printf("/%zdMb", N >> 20);
}
if (size_t FF = Corpus.NumInputsThatTouchFocusFunction())
Printf(" focus: %zd", FF);
}
if (TmpMaxMutationLen)
Printf(" lim: %zd", TmpMaxMutationLen);
if (Units)
Printf(" units: %zd", Units);
Printf(" exec/s: %zd", ExecPerSec);
Printf(" rss: %zdMb", GetPeakRSSMb());
Printf("%s", End);
}
void Fuzzer::PrintFinalStats() {
if (Options.PrintFullCoverage)
TPC.PrintCoverage(/*PrintAllCounters=*/true);
if (Options.PrintCoverage)
TPC.PrintCoverage(/*PrintAllCounters=*/false);
if (Options.PrintCorpusStats)
Corpus.PrintStats();
if (!Options.PrintFinalStats)
return;
size_t ExecPerSec = execPerSec();
Printf("stat::number_of_executed_units: %zd\n", TotalNumberOfRuns);
Printf("stat::average_exec_per_sec: %zd\n", ExecPerSec);
Printf("stat::new_units_added: %zd\n", NumberOfNewUnitsAdded);
Printf("stat::slowest_unit_time_sec: %zd\n", TimeOfLongestUnitInSeconds);
Printf("stat::peak_rss_mb: %zd\n", GetPeakRSSMb());
}
void Fuzzer::SetMaxInputLen(size_t MaxInputLen) {
assert(this->MaxInputLen == 0); // Can only reset MaxInputLen from 0 to non-0.
assert(MaxInputLen);
this->MaxInputLen = MaxInputLen;
this->MaxMutationLen = MaxInputLen;
AllocateCurrentUnitData();
Printf("INFO: -max_len is not provided; "
"libFuzzer will not generate inputs larger than %zd bytes\n",
MaxInputLen);
}
void Fuzzer::SetMaxMutationLen(size_t MaxMutationLen) {
assert(MaxMutationLen && MaxMutationLen <= MaxInputLen);
this->MaxMutationLen = MaxMutationLen;
}
void Fuzzer::CheckExitOnSrcPosOrItem() {
if (!Options.ExitOnSrcPos.empty()) {
static auto *PCsSet = new std::set<uintptr_t>;
auto HandlePC = [&](const TracePC::PCTableEntry *TE) {
if (!PCsSet->insert(TE->PC).second)
return;
std::string Descr = DescribePC("%F %L", TE->PC + 1);
if (Descr.find(Options.ExitOnSrcPos) != std::string::npos) {
Printf("INFO: found line matching '%s', exiting.\n",
Options.ExitOnSrcPos.c_str());
_Exit(0);
}
};
TPC.ForEachObservedPC(HandlePC);
}
if (!Options.ExitOnItem.empty()) {
if (Corpus.HasUnit(Options.ExitOnItem)) {
Printf("INFO: found item with checksum '%s', exiting.\n",
Options.ExitOnItem.c_str());
_Exit(0);
}
}
}
void Fuzzer::RereadOutputCorpus(size_t MaxSize) {
if (Options.OutputCorpus.empty() || !Options.ReloadIntervalSec)
return;
std::vector<Unit> AdditionalCorpus;
std::vector<std::string> AdditionalCorpusPaths;
ReadDirToVectorOfUnits(
Options.OutputCorpus.c_str(), &AdditionalCorpus,
&EpochOfLastReadOfOutputCorpus, MaxSize,
/*ExitOnError*/ false,
(Options.Verbosity >= 2 ? &AdditionalCorpusPaths : nullptr));
if (Options.Verbosity >= 2)
Printf("Reload: read %zd new units.\n", AdditionalCorpus.size());
bool Reloaded = false;
for (size_t i = 0; i != AdditionalCorpus.size(); ++i) {
auto &U = AdditionalCorpus[i];
if (U.size() > MaxSize)
U.resize(MaxSize);
if (!Corpus.HasUnit(U)) {
if (RunOne(U.data(), U.size())) {
CheckExitOnSrcPosOrItem();
Reloaded = true;
if (Options.Verbosity >= 2)
Printf("Reloaded %s\n", AdditionalCorpusPaths[i].c_str());
}
}
}
if (Reloaded)
PrintStats("RELOAD");
}
void Fuzzer::PrintPulseAndReportSlowInput(const uint8_t *Data, size_t Size) {
auto TimeOfUnit =
duration_cast<seconds>(UnitStopTime - UnitStartTime).count();
if (!(TotalNumberOfRuns & (TotalNumberOfRuns - 1)) &&
secondsSinceProcessStartUp() >= 2)
PrintStats("pulse ");
auto Threshhold =
static_cast<long>(static_cast<double>(TimeOfLongestUnitInSeconds) * 1.1);
if (TimeOfUnit > Threshhold && TimeOfUnit >= Options.ReportSlowUnits) {
TimeOfLongestUnitInSeconds = TimeOfUnit;
Printf("Slowest unit: %zd s:\n", TimeOfLongestUnitInSeconds);
WriteUnitToFileWithPrefix({Data, Data + Size}, "slow-unit-");
}
}
static void WriteFeatureSetToFile(const std::string &FeaturesDir,
const std::string &FileName,
const std::vector<uint32_t> &FeatureSet) {
if (FeaturesDir.empty() || FeatureSet.empty()) return;
WriteToFile(reinterpret_cast<const uint8_t *>(FeatureSet.data()),
FeatureSet.size() * sizeof(FeatureSet[0]),
DirPlusFile(FeaturesDir, FileName));
}
static void RenameFeatureSetFile(const std::string &FeaturesDir,
const std::string &OldFile,
const std::string &NewFile) {
if (FeaturesDir.empty()) return;
RenameFile(DirPlusFile(FeaturesDir, OldFile),
DirPlusFile(FeaturesDir, NewFile));
}
static void WriteEdgeToMutationGraphFile(const std::string &MutationGraphFile,
const InputInfo *II,
const InputInfo *BaseII,
const std::string &MS) {
if (MutationGraphFile.empty())
return;
std::string Sha1 = Sha1ToString(II->Sha1);
std::string OutputString;
// Add a new vertex.
OutputString.append("\"");
OutputString.append(Sha1);
OutputString.append("\"\n");
// Add a new edge if there is base input.
if (BaseII) {
std::string BaseSha1 = Sha1ToString(BaseII->Sha1);
OutputString.append("\"");
OutputString.append(BaseSha1);
OutputString.append("\" -> \"");
OutputString.append(Sha1);
OutputString.append("\" [label=\"");
OutputString.append(MS);
OutputString.append("\"];\n");
}
AppendToFile(OutputString, MutationGraphFile);
}
bool Fuzzer::RunOne(const uint8_t *Data, size_t Size, bool MayDeleteFile,
InputInfo *II, bool ForceAddToCorpus,
bool *FoundUniqFeatures) {
if (!Size)
return false;
// Largest input length should be INT_MAX.
assert(Size < std::numeric_limits<uint32_t>::max());
ExecuteCallback(Data, Size);
auto TimeOfUnit = duration_cast<microseconds>(UnitStopTime - UnitStartTime);
UniqFeatureSetTmp.clear();
size_t FoundUniqFeaturesOfII = 0;
size_t NumUpdatesBefore = Corpus.NumFeatureUpdates();
TPC.CollectFeatures([&](uint32_t Feature) {
if (Corpus.AddFeature(Feature, static_cast<uint32_t>(Size), Options.Shrink))
UniqFeatureSetTmp.push_back(Feature);
if (Options.Entropic)
Corpus.UpdateFeatureFrequency(II, Feature);
if (Options.ReduceInputs && II && !II->NeverReduce)
if (std::binary_search(II->UniqFeatureSet.begin(),
II->UniqFeatureSet.end(), Feature))
FoundUniqFeaturesOfII++;
});
if (FoundUniqFeatures)
*FoundUniqFeatures = FoundUniqFeaturesOfII;
PrintPulseAndReportSlowInput(Data, Size);
size_t NumNewFeatures = Corpus.NumFeatureUpdates() - NumUpdatesBefore;
if (NumNewFeatures || ForceAddToCorpus) {
TPC.UpdateObservedPCs();
auto NewII =
Corpus.AddToCorpus({Data, Data + Size}, NumNewFeatures, MayDeleteFile,
TPC.ObservedFocusFunction(), ForceAddToCorpus,
TimeOfUnit, UniqFeatureSetTmp, DFT, II);
WriteFeatureSetToFile(Options.FeaturesDir, Sha1ToString(NewII->Sha1),
NewII->UniqFeatureSet);
WriteEdgeToMutationGraphFile(Options.MutationGraphFile, NewII, II,
MD.MutationSequence());
return true;
}
if (II && FoundUniqFeaturesOfII &&
II->DataFlowTraceForFocusFunction.empty() &&
FoundUniqFeaturesOfII == II->UniqFeatureSet.size() &&
II->U.size() > Size) {
auto OldFeaturesFile = Sha1ToString(II->Sha1);
Corpus.Replace(II, {Data, Data + Size});
RenameFeatureSetFile(Options.FeaturesDir, OldFeaturesFile,
Sha1ToString(II->Sha1));
return true;
}
return false;
}
void Fuzzer::TPCUpdateObservedPCs() { TPC.UpdateObservedPCs(); }
size_t Fuzzer::GetCurrentUnitInFuzzingThead(const uint8_t **Data) const {
assert(InFuzzingThread());
*Data = CurrentUnitData;
return CurrentUnitSize;
}
void Fuzzer::CrashOnOverwrittenData() {
Printf("==%d== ERROR: libFuzzer: fuzz target overwrites its const input\n",
GetPid());
PrintStackTrace();
Printf("SUMMARY: libFuzzer: overwrites-const-input\n");
DumpCurrentUnit("crash-");
PrintFinalStats();
_Exit(Options.ErrorExitCode); // Stop right now.
}
// Compare two arrays, but not all bytes if the arrays are large.
static bool LooseMemeq(const uint8_t *A, const uint8_t *B, size_t Size) {
const size_t Limit = 64;
if (Size <= 64)
return !memcmp(A, B, Size);
// Compare first and last Limit/2 bytes.
return !memcmp(A, B, Limit / 2) &&
!memcmp(A + Size - Limit / 2, B + Size - Limit / 2, Limit / 2);
}
// This method is not inlined because it would cause a test to fail where it
// is part of the stack unwinding. See D97975 for details.
ATTRIBUTE_NOINLINE void Fuzzer::ExecuteCallback(const uint8_t *Data,
size_t Size) {
TPC.RecordInitialStack();
TotalNumberOfRuns++;
assert(InFuzzingThread());
// We copy the contents of Unit into a separate heap buffer
// so that we reliably find buffer overflows in it.
uint8_t *DataCopy = new uint8_t[Size];
memcpy(DataCopy, Data, Size);
if (EF->__msan_unpoison)
EF->__msan_unpoison(DataCopy, Size);
if (EF->__msan_unpoison_param)
EF->__msan_unpoison_param(2);
if (CurrentUnitData && CurrentUnitData != Data)
memcpy(CurrentUnitData, Data, Size);
CurrentUnitSize = Size;
{
ScopedEnableMsanInterceptorChecks S;
AllocTracer.Start(Options.TraceMalloc);
UnitStartTime = system_clock::now();
TPC.ResetMaps();
RunningUserCallback = true;
int Res = CB(DataCopy, Size);
RunningUserCallback = false;
UnitStopTime = system_clock::now();
(void)Res;
assert(Res == 0);
HasMoreMallocsThanFrees = AllocTracer.Stop();
}
if (!LooseMemeq(DataCopy, Data, Size))
CrashOnOverwrittenData();
CurrentUnitSize = 0;
delete[] DataCopy;
}
std::string Fuzzer::WriteToOutputCorpus(const Unit &U) {
if (Options.OnlyASCII)
assert(IsASCII(U));
if (Options.OutputCorpus.empty())
return "";
std::string Path = DirPlusFile(Options.OutputCorpus, Hash(U));
WriteToFile(U, Path);
if (Options.Verbosity >= 2)
Printf("Written %zd bytes to %s\n", U.size(), Path.c_str());
return Path;
}
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::PrintStatusForNewUnit(const Unit &U, const char *Text) {
if (!Options.PrintNEW)
return;
PrintStats(Text, "");
if (Options.Verbosity) {
Printf(" L: %zd/%zd ", U.size(), Corpus.MaxInputSize());
MD.PrintMutationSequence(Options.Verbosity >= 2);
Printf("\n");
}
}
void Fuzzer::ReportNewCoverage(InputInfo *II, const Unit &U) {
II->NumSuccessfullMutations++;
MD.RecordSuccessfulMutationSequence();
PrintStatusForNewUnit(U, II->Reduced ? "REDUCE" : "NEW ");
WriteToOutputCorpus(U);
NumberOfNewUnitsAdded++;
CheckExitOnSrcPosOrItem(); // Check only after the unit is saved to corpus.
LastCorpusUpdateRun = TotalNumberOfRuns;
}
// Tries detecting a memory leak on the particular input that we have just
// executed before calling this function.
void Fuzzer::TryDetectingAMemoryLeak(const uint8_t *Data, size_t Size,
bool DuringInitialCorpusExecution) {
if (!HasMoreMallocsThanFrees)
return; // mallocs==frees, a leak is unlikely.
if (!Options.DetectLeaks)
return;
if (!DuringInitialCorpusExecution &&
TotalNumberOfRuns >= Options.MaxNumberOfRuns)
return;
if (!&(EF->__lsan_enable) || !&(EF->__lsan_disable) ||
!(EF->__lsan_do_recoverable_leak_check))
return; // No lsan.
// Run the target once again, but with lsan disabled so that if there is
// a real leak we do not report it twice.
EF->__lsan_disable();
ExecuteCallback(Data, Size);
EF->__lsan_enable();
if (!HasMoreMallocsThanFrees)
return; // a leak is unlikely.
if (NumberOfLeakDetectionAttempts++ > 1000) {
Options.DetectLeaks = false;
Printf("INFO: libFuzzer disabled leak detection after every mutation.\n"
" Most likely the target function accumulates allocated\n"
" memory in a global state w/o actually leaking it.\n"
" You may try running this binary with -trace_malloc=[12]"
" to get a trace of mallocs and frees.\n"
" If LeakSanitizer is enabled in this process it will still\n"
" run on the process shutdown.\n");
return;
}
// Now perform the actual lsan pass. This is expensive and we must ensure
// we don't call it too often.
if (EF->__lsan_do_recoverable_leak_check()) { // Leak is found, report it.
if (DuringInitialCorpusExecution)
Printf("\nINFO: a leak has been found in the initial corpus.\n\n");
Printf("INFO: to ignore leaks on libFuzzer side use -detect_leaks=0.\n\n");
CurrentUnitSize = Size;
DumpCurrentUnit("leak-");
PrintFinalStats();
_Exit(Options.ErrorExitCode); // not exit() to disable lsan further on.
}
}
void Fuzzer::MutateAndTestOne() {
MD.StartMutationSequence();
auto &II = Corpus.ChooseUnitToMutate(MD.GetRand());
if (Options.DoCrossOver) {
auto &CrossOverII = Corpus.ChooseUnitToCrossOverWith(
MD.GetRand(), Options.CrossOverUniformDist);
MD.SetCrossOverWith(&CrossOverII.U);
}
const auto &U = II.U;
memcpy(BaseSha1, II.Sha1, sizeof(BaseSha1));
assert(CurrentUnitData);
size_t Size = U.size();
assert(Size <= MaxInputLen && "Oversized Unit");
memcpy(CurrentUnitData, U.data(), Size);
assert(MaxMutationLen > 0);
size_t CurrentMaxMutationLen =
Min(MaxMutationLen, Max(U.size(), TmpMaxMutationLen));
assert(CurrentMaxMutationLen > 0);
for (int i = 0; i < Options.MutateDepth; i++) {
if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
break;
MaybeExitGracefully();
size_t NewSize = 0;
if (II.HasFocusFunction && !II.DataFlowTraceForFocusFunction.empty() &&
Size <= CurrentMaxMutationLen)
NewSize = MD.MutateWithMask(CurrentUnitData, Size, Size,
II.DataFlowTraceForFocusFunction);
// If MutateWithMask either failed or wasn't called, call default Mutate.
if (!NewSize)
NewSize = MD.Mutate(CurrentUnitData, Size, CurrentMaxMutationLen);
assert(NewSize > 0 && "Mutator returned empty unit");
assert(NewSize <= CurrentMaxMutationLen && "Mutator return oversized unit");
Size = NewSize;
II.NumExecutedMutations++;
Corpus.IncrementNumExecutedMutations();
bool FoundUniqFeatures = false;
bool NewCov = RunOne(CurrentUnitData, Size, /*MayDeleteFile=*/true, &II,
/*ForceAddToCorpus*/ false, &FoundUniqFeatures);
TryDetectingAMemoryLeak(CurrentUnitData, Size,
/*DuringInitialCorpusExecution*/ false);
if (NewCov) {
ReportNewCoverage(&II, {CurrentUnitData, CurrentUnitData + Size});
break; // We will mutate this input more in the next rounds.
}
if (Options.ReduceDepth && !FoundUniqFeatures)
break;
}
II.NeedsEnergyUpdate = true;
}
void Fuzzer::PurgeAllocator() {
if (Options.PurgeAllocatorIntervalSec < 0 || !EF->__sanitizer_purge_allocator)
return;
if (duration_cast<seconds>(system_clock::now() -
LastAllocatorPurgeAttemptTime)
.count() < Options.PurgeAllocatorIntervalSec)
return;
if (Options.RssLimitMb <= 0 ||
GetPeakRSSMb() > static_cast<size_t>(Options.RssLimitMb) / 2)
EF->__sanitizer_purge_allocator();
LastAllocatorPurgeAttemptTime = system_clock::now();
}
void Fuzzer::ReadAndExecuteSeedCorpora(std::vector<SizedFile> &CorporaFiles) {
const size_t kMaxSaneLen = 1 << 20;
const size_t kMinDefaultLen = 4096;
size_t MaxSize = 0;
size_t MinSize = -1;
size_t TotalSize = 0;
for (auto &File : CorporaFiles) {
MaxSize = Max(File.Size, MaxSize);
MinSize = Min(File.Size, MinSize);
TotalSize += File.Size;
}
if (Options.MaxLen == 0)
SetMaxInputLen(std::min(std::max(kMinDefaultLen, MaxSize), kMaxSaneLen));
assert(MaxInputLen > 0);
// Test the callback with empty input and never try it again.
uint8_t dummy = 0;
ExecuteCallback(&dummy, 0);
if (CorporaFiles.empty()) {
Printf("INFO: A corpus is not provided, starting from an empty corpus\n");
Unit U({'\n'}); // Valid ASCII input.
RunOne(U.data(), U.size());
} else {
Printf("INFO: seed corpus: files: %zd min: %zdb max: %zdb total: %zdb"
" rss: %zdMb\n",
CorporaFiles.size(), MinSize, MaxSize, TotalSize, GetPeakRSSMb());
if (Options.ShuffleAtStartUp)
std::shuffle(CorporaFiles.begin(), CorporaFiles.end(), MD.GetRand());
if (Options.PreferSmall) {
std::stable_sort(CorporaFiles.begin(), CorporaFiles.end());
assert(CorporaFiles.front().Size <= CorporaFiles.back().Size);
}
// Load and execute inputs one by one.
for (auto &SF : CorporaFiles) {
auto U = FileToVector(SF.File, MaxInputLen, /*ExitOnError=*/false);
assert(U.size() <= MaxInputLen);
RunOne(U.data(), U.size(), /*MayDeleteFile*/ false, /*II*/ nullptr,
/*ForceAddToCorpus*/ Options.KeepSeed,
/*FoundUniqFeatures*/ nullptr);
CheckExitOnSrcPosOrItem();
TryDetectingAMemoryLeak(U.data(), U.size(),
/*DuringInitialCorpusExecution*/ true);
}
}
PrintStats("INITED");
if (!Options.FocusFunction.empty()) {
Printf("INFO: %zd/%zd inputs touch the focus function\n",
Corpus.NumInputsThatTouchFocusFunction(), Corpus.size());
if (!Options.DataFlowTrace.empty())
Printf("INFO: %zd/%zd inputs have the Data Flow Trace\n",
Corpus.NumInputsWithDataFlowTrace(),
Corpus.NumInputsThatTouchFocusFunction());
}
if (Corpus.empty() && Options.MaxNumberOfRuns) {
Printf("ERROR: no interesting inputs were found. "
"Is the code instrumented for coverage? Exiting.\n");
exit(1);
}
}
void Fuzzer::Loop(std::vector<SizedFile> &CorporaFiles) {
auto FocusFunctionOrAuto = Options.FocusFunction;
DFT.Init(Options.DataFlowTrace, &FocusFunctionOrAuto, CorporaFiles,
MD.GetRand());
TPC.SetFocusFunction(FocusFunctionOrAuto);
ReadAndExecuteSeedCorpora(CorporaFiles);
DFT.Clear(); // No need for DFT any more.
TPC.SetPrintNewPCs(Options.PrintNewCovPcs);
TPC.SetPrintNewFuncs(Options.PrintNewCovFuncs);
system_clock::time_point LastCorpusReload = system_clock::now();
TmpMaxMutationLen =
Min(MaxMutationLen, Max(size_t(4), Corpus.MaxInputSize()));
while (true) {
auto Now = system_clock::now();
if (!Options.StopFile.empty() &&
!FileToVector(Options.StopFile, 1, false).empty())
break;
if (duration_cast<seconds>(Now - LastCorpusReload).count() >=
Options.ReloadIntervalSec) {
RereadOutputCorpus(MaxInputLen);
LastCorpusReload = system_clock::now();
}
if (TotalNumberOfRuns >= Options.MaxNumberOfRuns)
break;
if (TimedOut())
break;
// Update TmpMaxMutationLen
if (Options.LenControl) {
if (TmpMaxMutationLen < MaxMutationLen &&
TotalNumberOfRuns - LastCorpusUpdateRun >
Options.LenControl * Log(TmpMaxMutationLen)) {
TmpMaxMutationLen =
Min(MaxMutationLen, TmpMaxMutationLen + Log(TmpMaxMutationLen));
LastCorpusUpdateRun = TotalNumberOfRuns;
}
} else {
TmpMaxMutationLen = MaxMutationLen;
}
// Perform several mutations and runs.
MutateAndTestOne();
PurgeAllocator();
}
PrintStats("DONE ", "\n");
MD.PrintRecommendedDictionary();
}
void Fuzzer::MinimizeCrashLoop(const Unit &U) {
if (U.size() <= 1)
return;
while (!TimedOut() && TotalNumberOfRuns < Options.MaxNumberOfRuns) {
MD.StartMutationSequence();
memcpy(CurrentUnitData, U.data(), U.size());
for (int i = 0; i < Options.MutateDepth; i++) {
size_t NewSize = MD.Mutate(CurrentUnitData, U.size(), MaxMutationLen);
assert(NewSize > 0 && NewSize <= MaxMutationLen);
ExecuteCallback(CurrentUnitData, NewSize);
PrintPulseAndReportSlowInput(CurrentUnitData, NewSize);
TryDetectingAMemoryLeak(CurrentUnitData, NewSize,
/*DuringInitialCorpusExecution*/ false);
}
}
}
} // namespace fuzzer
extern "C" {
ATTRIBUTE_INTERFACE size_t
LLVMFuzzerMutate(uint8_t *Data, size_t Size, size_t MaxSize) {
assert(fuzzer::F);
return fuzzer::F->GetMD().DefaultMutate(Data, Size, MaxSize);
}
} // extern "C"
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