compiler-rt/lib/fuzzer/FuzzerFork.cpp

   1 //===- FuzzerFork.cpp - run fuzzing in separate subprocesses --------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 // Spawn and orchestrate separate fuzzing processes.
   9 //===----------------------------------------------------------------------===//
  10
  11 #include "FuzzerCommand.h"
  12 #include "FuzzerFork.h"
  13 #include "FuzzerIO.h"
  14 #include "FuzzerInternal.h"
  15 #include "FuzzerMerge.h"
  16 #include "FuzzerSHA1.h"
  17 #include "FuzzerTracePC.h"
  18 #include "FuzzerUtil.h"
  19
  20 #include <atomic>
  21 #include <chrono>
  22 #include <condition_variable>
  23 #include <fstream>
  24 #include <memory>
  25 #include <mutex>
  26 #include <queue>
  27 #include <sstream>
  28 #include <thread>
  29
  30 namespace fuzzer {
  31
  32 struct Stats {
  33   size_t number_of_executed_units = 0;
  34   size_t peak_rss_mb = 0;
  35   size_t average_exec_per_sec = 0;
  36 };
  37
  38 static Stats ParseFinalStatsFromLog(const std::string &LogPath) {
  39   std::ifstream In(LogPath);
  40   std::string Line;
  41   Stats Res;
  42   struct {
  43     const char *Name;
  44     size_t *Var;
  45   } NameVarPairs[] = {
  46       {"stat::number_of_executed_units:", &Res.number_of_executed_units},
  47       {"stat::peak_rss_mb:", &Res.peak_rss_mb},
  48       {"stat::average_exec_per_sec:", &Res.average_exec_per_sec},
  49       {nullptr, nullptr},
  50   };
  51   while (std::getline(In, Line, '\n')) {
  52     if (Line.find("stat::") != 0) continue;
  53     std::istringstream ISS(Line);
  54     std::string Name;
  55     size_t Val;
  56     ISS >> Name >> Val;
  57     for (size_t i = 0; NameVarPairs[i].Name; i++)
  58       if (Name == NameVarPairs[i].Name)
  59         *NameVarPairs[i].Var = Val;
  60   }
  61   return Res;
  62 }
  63
  64 struct FuzzJob {
  65   // Inputs.
  66   Command Cmd;
  67   std::string CorpusDir;
  68   std::string FeaturesDir;
  69   std::string LogPath;
  70   std::string SeedListPath;
  71   std::string CFPath;
  72   size_t      JobId;
  73
  74   int         DftTimeInSeconds = 0;
  75
  76   // Fuzzing Outputs.
  77   int ExitCode;
  78
  79   ~FuzzJob() {
  80     RemoveFile(CFPath);
  81     RemoveFile(LogPath);
  82     RemoveFile(SeedListPath);
  83     RmDirRecursive(CorpusDir);
  84     RmDirRecursive(FeaturesDir);
  85   }
  86 };
  87
  88 struct GlobalEnv {
  89   std::vector<std::string> Args;
  90   std::vector<std::string> CorpusDirs;
  91   std::string MainCorpusDir;
  92   std::string TempDir;
  93   std::string DFTDir;
  94   std::string DataFlowBinary;
  95   std::set<uint32_t> Features, Cov;
  96   std::set<std::string> FilesWithDFT;
  97   std::vector<std::string> Files;
  98   std::vector<std::size_t> FilesSizes;
  99   Random *Rand;
 100   std::chrono::system_clock::time_point ProcessStartTime;
 101   int Verbosity = 0;
 102   int Group = 0;
 103   int NumCorpuses = 8;
 104
 105   size_t NumTimeouts = 0;
 106   size_t NumOOMs = 0;
 107   size_t NumCrashes = 0;
 108
 109
 110   size_t NumRuns = 0;
 111
 112   std::string StopFile() { return DirPlusFile(TempDir, "STOP"); }
 113
 114   size_t secondsSinceProcessStartUp() const {
 115     return std::chrono::duration_cast<std::chrono::seconds>(
 116                std::chrono::system_clock::now() - ProcessStartTime)
 117         .count();
 118   }
 119
 120   FuzzJob *CreateNewJob(size_t JobId) {
 121     Command Cmd(Args);
 122     Cmd.removeFlag("fork");
 123     Cmd.removeFlag("runs");
 124     Cmd.removeFlag("collect_data_flow");
 125     for (auto &C : CorpusDirs) // Remove all corpora from the args.
 126       Cmd.removeArgument(C);
 127     Cmd.addFlag("reload", "0");  // working in an isolated dir, no reload.
 128     Cmd.addFlag("print_final_stats", "1");
 129     Cmd.addFlag("print_funcs", "0");  // no need to spend time symbolizing.
 130     Cmd.addFlag("max_total_time", std::to_string(std::min((size_t)300, JobId)));
 131     Cmd.addFlag("stop_file", StopFile());
 132     if (!DataFlowBinary.empty()) {
 133       Cmd.addFlag("data_flow_trace", DFTDir);
 134       if (!Cmd.hasFlag("focus_function"))
 135         Cmd.addFlag("focus_function", "auto");
 136     }
 137     auto Job = new FuzzJob;
 138     std::string Seeds;
 139     if (size_t CorpusSubsetSize =
 140             std::min(Files.size(), (size_t)sqrt(Files.size() + 2))) {
 141       auto Time1 = std::chrono::system_clock::now();
 142       if (Group) { // whether to group the corpus.
 143         size_t AverageCorpusSize = Files.size() / NumCorpuses + 1;
 144         size_t StartIndex = ((JobId - 1) % NumCorpuses) * AverageCorpusSize;
 145         for (size_t i = 0; i < CorpusSubsetSize; i++) {
 146           size_t RandNum = (*Rand)(AverageCorpusSize);
 147           size_t Index = RandNum + StartIndex;
 148           Index = Index < Files.size() ? Index
 149                                        : Rand->SkewTowardsLast(Files.size());
 150           auto &SF = Files[Index];
 151           Seeds += (Seeds.empty() ? "" : ",") + SF;
 152           CollectDFT(SF);
 153         }
 154       } else {
 155         for (size_t i = 0; i < CorpusSubsetSize; i++) {
 156           auto &SF = Files[Rand->SkewTowardsLast(Files.size())];
 157           Seeds += (Seeds.empty() ? "" : ",") + SF;
 158           CollectDFT(SF);
 159         }
 160       }
 161       auto Time2 = std::chrono::system_clock::now();
 162       auto DftTimeInSeconds = duration_cast<seconds>(Time2 - Time1).count();
 163       assert(DftTimeInSeconds < std::numeric_limits<int>::max());
 164       Job->DftTimeInSeconds = static_cast<int>(DftTimeInSeconds);
 165     }
 166     if (!Seeds.empty()) {
 167       Job->SeedListPath =
 168           DirPlusFile(TempDir, std::to_string(JobId) + ".seeds");
 169       WriteToFile(Seeds, Job->SeedListPath);
 170       Cmd.addFlag("seed_inputs", "@" + Job->SeedListPath);
 171     }
 172     Job->LogPath = DirPlusFile(TempDir, std::to_string(JobId) + ".log");
 173     Job->CorpusDir = DirPlusFile(TempDir, "C" + std::to_string(JobId));
 174     Job->FeaturesDir = DirPlusFile(TempDir, "F" + std::to_string(JobId));
 175     Job->CFPath = DirPlusFile(TempDir, std::to_string(JobId) + ".merge");
 176     Job->JobId = JobId;
 177
 178
 179     Cmd.addArgument(Job->CorpusDir);
 180     Cmd.addFlag("features_dir", Job->FeaturesDir);
 181
 182     for (auto &D : {Job->CorpusDir, Job->FeaturesDir}) {
 183       RmDirRecursive(D);
 184       MkDir(D);
 185     }
 186
 187     Cmd.setOutputFile(Job->LogPath);
 188     Cmd.combineOutAndErr();
 189
 190     Job->Cmd = Cmd;
 191
 192     if (Verbosity >= 2)
 193       Printf("Job %zd/%p Created: %s\n", JobId, Job,
 194              Job->Cmd.toString().c_str());
 195     // Start from very short runs and gradually increase them.
 196     return Job;
 197   }
 198
 199   void RunOneMergeJob(FuzzJob *Job) {
 200     auto Stats = ParseFinalStatsFromLog(Job->LogPath);
 201     NumRuns += Stats.number_of_executed_units;
 202
 203     std::vector<SizedFile> TempFiles, MergeCandidates;
 204     // Read all newly created inputs and their feature sets.
 205     // Choose only those inputs that have new features.
 206     GetSizedFilesFromDir(Job->CorpusDir, &TempFiles);
 207     std::sort(TempFiles.begin(), TempFiles.end());
 208     for (auto &F : TempFiles) {
 209       auto FeatureFile = F.File;
 210       FeatureFile.replace(0, Job->CorpusDir.size(), Job->FeaturesDir);
 211       auto FeatureBytes = FileToVector(FeatureFile, 0, false);
 212       assert((FeatureBytes.size() % sizeof(uint32_t)) == 0);
 213       std::vector<uint32_t> NewFeatures(FeatureBytes.size() / sizeof(uint32_t));
 214       memcpy(NewFeatures.data(), FeatureBytes.data(), FeatureBytes.size());
 215       for (auto Ft : NewFeatures) {
 216         if (!Features.count(Ft)) {
 217           MergeCandidates.push_back(F);
 218           break;
 219         }
 220       }
 221     }
 222     // if (!FilesToAdd.empty() || Job->ExitCode != 0)
 223     Printf("#%zd: cov: %zd ft: %zd corp: %zd exec/s: %zd "
 224            "oom/timeout/crash: %zd/%zd/%zd time: %zds job: %zd dft_time: %d\n",
 225            NumRuns, Cov.size(), Features.size(), Files.size(),
 226            Stats.average_exec_per_sec, NumOOMs, NumTimeouts, NumCrashes,
 227            secondsSinceProcessStartUp(), Job->JobId, Job->DftTimeInSeconds);
 228
 229     if (MergeCandidates.empty()) return;
 230
 231     std::vector<std::string> FilesToAdd;
 232     std::set<uint32_t> NewFeatures, NewCov;
 233     bool IsSetCoverMerge =
 234         !Job->Cmd.getFlagValue("set_cover_merge").compare("1");
 235     CrashResistantMerge(Args, {}, MergeCandidates, &FilesToAdd, Features,
 236                         &NewFeatures, Cov, &NewCov, Job->CFPath, false,
 237                         IsSetCoverMerge);
 238     for (auto &Path : FilesToAdd) {
 239       auto U = FileToVector(Path);
 240       auto NewPath = DirPlusFile(MainCorpusDir, Hash(U));
 241       WriteToFile(U, NewPath);
 242       if (Group) { // Insert the queue according to the size of the seed.
 243         size_t UnitSize = U.size();
 244         auto Idx =
 245             std::upper_bound(FilesSizes.begin(), FilesSizes.end(), UnitSize) -
 246             FilesSizes.begin();
 247         FilesSizes.insert(FilesSizes.begin() + Idx, UnitSize);
 248         Files.insert(Files.begin() + Idx, NewPath);
 249       } else {
 250         Files.push_back(NewPath);
 251       }
 252     }
 253     Features.insert(NewFeatures.begin(), NewFeatures.end());
 254     Cov.insert(NewCov.begin(), NewCov.end());
 255     for (auto Idx : NewCov)
 256       if (auto *TE = TPC.PCTableEntryByIdx(Idx))
 257         if (TPC.PcIsFuncEntry(TE))
 258           PrintPC("  NEW_FUNC: %p %F %L\n", "",
 259                   TPC.GetNextInstructionPc(TE->PC));
 260   }
 261
 262   void CollectDFT(const std::string &InputPath) {
 263     if (DataFlowBinary.empty()) return;
 264     if (!FilesWithDFT.insert(InputPath).second) return;
 265     Command Cmd(Args);
 266     Cmd.removeFlag("fork");
 267     Cmd.removeFlag("runs");
 268     Cmd.addFlag("data_flow_trace", DFTDir);
 269     Cmd.addArgument(InputPath);
 270     for (auto &C : CorpusDirs) // Remove all corpora from the args.
 271       Cmd.removeArgument(C);
 272     Cmd.setOutputFile(DirPlusFile(TempDir, "dft.log"));
 273     Cmd.combineOutAndErr();
 274     // Printf("CollectDFT: %s\n", Cmd.toString().c_str());
 275     ExecuteCommand(Cmd);
 276   }
 277
 278 };
 279
 280 struct JobQueue {
 281   std::queue<FuzzJob *> Qu;
 282   std::mutex Mu;
 283   std::condition_variable Cv;
 284
 285   void Push(FuzzJob *Job) {
 286     {
 287       std::lock_guard<std::mutex> Lock(Mu);
 288       Qu.push(Job);
 289     }
 290     Cv.notify_one();
 291   }
 292   FuzzJob *Pop() {
 293     std::unique_lock<std::mutex> Lk(Mu);
 294     // std::lock_guard<std::mutex> Lock(Mu);
 295     Cv.wait(Lk, [&]{return !Qu.empty();});
 296     assert(!Qu.empty());
 297     auto Job = Qu.front();
 298     Qu.pop();
 299     return Job;
 300   }
 301 };
 302
 303 void WorkerThread(JobQueue *FuzzQ, JobQueue *MergeQ) {
 304   while (auto Job = FuzzQ->Pop()) {
 305     // Printf("WorkerThread: job %p\n", Job);
 306     Job->ExitCode = ExecuteCommand(Job->Cmd);
 307     MergeQ->Push(Job);
 308   }
 309 }
 310
 311 // This is just a skeleton of an experimental -fork=1 feature.
 312 void FuzzWithFork(Random &Rand, const FuzzingOptions &Options,
 313                   const std::vector<std::string> &Args,
 314                   const std::vector<std::string> &CorpusDirs, int NumJobs) {
 315   Printf("INFO: -fork=%d: fuzzing in separate process(s)\n", NumJobs);
 316
 317   GlobalEnv Env;
 318   Env.Args = Args;
 319   Env.CorpusDirs = CorpusDirs;
 320   Env.Rand = &Rand;
 321   Env.Verbosity = Options.Verbosity;
 322   Env.ProcessStartTime = std::chrono::system_clock::now();
 323   Env.DataFlowBinary = Options.CollectDataFlow;
 324   Env.Group = Options.ForkCorpusGroups;
 325
 326   std::vector<SizedFile> SeedFiles;
 327   for (auto &Dir : CorpusDirs)
 328     GetSizedFilesFromDir(Dir, &SeedFiles);
 329   std::sort(SeedFiles.begin(), SeedFiles.end());
 330   Env.TempDir = TempPath("FuzzWithFork", ".dir");
 331   Env.DFTDir = DirPlusFile(Env.TempDir, "DFT");
 332   RmDirRecursive(Env.TempDir);  // in case there is a leftover from old runs.
 333   MkDir(Env.TempDir);
 334   MkDir(Env.DFTDir);
 335
 336
 337   if (CorpusDirs.empty())
 338     MkDir(Env.MainCorpusDir = DirPlusFile(Env.TempDir, "C"));
 339   else
 340     Env.MainCorpusDir = CorpusDirs[0];
 341
 342   if (Options.KeepSeed) {
 343     for (auto &File : SeedFiles)
 344       Env.Files.push_back(File.File);
 345   } else {
 346     auto CFPath = DirPlusFile(Env.TempDir, "merge.txt");
 347     std::set<uint32_t> NewFeatures, NewCov;
 348     CrashResistantMerge(Env.Args, {}, SeedFiles, &Env.Files, Env.Features,
 349                         &NewFeatures, Env.Cov, &NewCov, CFPath,
 350                         /*Verbose=*/false, /*IsSetCoverMerge=*/false);
 351     Env.Features.insert(NewFeatures.begin(), NewFeatures.end());
 352     Env.Cov.insert(NewFeatures.begin(), NewFeatures.end());
 353     RemoveFile(CFPath);
 354   }
 355
 356   if (Env.Group) {
 357     for (auto &path : Env.Files)
 358       Env.FilesSizes.push_back(FileSize(path));
 359   }
 360
 361   Printf("INFO: -fork=%d: %zd seed inputs, starting to fuzz in %s\n", NumJobs,
 362          Env.Files.size(), Env.TempDir.c_str());
 363
 364   int ExitCode = 0;
 365
 366   JobQueue FuzzQ, MergeQ;
 367
 368   auto StopJobs = [&]() {
 369     for (int i = 0; i < NumJobs; i++)
 370       FuzzQ.Push(nullptr);
 371     MergeQ.Push(nullptr);
 372     WriteToFile(Unit({1}), Env.StopFile());
 373   };
 374
 375   size_t MergeCycle = 20;
 376   size_t JobExecuted = 0;
 377   size_t JobId = 1;
 378   std::vector<std::thread> Threads;
 379   for (int t = 0; t < NumJobs; t++) {
 380     Threads.push_back(std::thread(WorkerThread, &FuzzQ, &MergeQ));
 381     FuzzQ.Push(Env.CreateNewJob(JobId++));
 382   }
 383
 384   while (true) {
 385     std::unique_ptr<FuzzJob> Job(MergeQ.Pop());
 386     if (!Job)
 387       break;
 388     ExitCode = Job->ExitCode;
 389     if (ExitCode == Options.InterruptExitCode) {
 390       Printf("==%lu== libFuzzer: a child was interrupted; exiting\n", GetPid());
 391       StopJobs();
 392       break;
 393     }
 394     Fuzzer::MaybeExitGracefully();
 395
 396     Env.RunOneMergeJob(Job.get());
 397
 398     // merge the corpus .
 399     JobExecuted++;
 400     if (Env.Group && JobExecuted >= MergeCycle) {
 401       std::vector<SizedFile> CurrentSeedFiles;
 402       for (auto &Dir : CorpusDirs)
 403         GetSizedFilesFromDir(Dir, &CurrentSeedFiles);
 404       std::sort(CurrentSeedFiles.begin(), CurrentSeedFiles.end());
 405
 406       auto CFPath = DirPlusFile(Env.TempDir, "merge.txt");
 407       std::set<uint32_t> TmpNewFeatures, TmpNewCov;
 408       std::set<uint32_t> TmpFeatures, TmpCov;
 409       Env.Files.clear();
 410       Env.FilesSizes.clear();
 411       CrashResistantMerge(Env.Args, {}, CurrentSeedFiles, &Env.Files,
 412                           TmpFeatures, &TmpNewFeatures, TmpCov, &TmpNewCov,
 413                           CFPath, /*Verbose=*/false, /*IsSetCoverMerge=*/false);
 414       for (auto &path : Env.Files)
 415         Env.FilesSizes.push_back(FileSize(path));
 416       RemoveFile(CFPath);
 417       JobExecuted = 0;
 418       MergeCycle += 5;
 419     }
 420
 421     // Since the number of corpus seeds will gradually increase, in order to
 422     // control the number in each group to be about three times the number of
 423     // seeds selected each time, the number of groups is dynamically adjusted.
 424     if (Env.Files.size() < 2000)
 425       Env.NumCorpuses = 12;
 426     else if (Env.Files.size() < 6000)
 427       Env.NumCorpuses = 20;
 428     else if (Env.Files.size() < 12000)
 429       Env.NumCorpuses = 32;
 430     else if (Env.Files.size() < 16000)
 431       Env.NumCorpuses = 40;
 432     else if (Env.Files.size() < 24000)
 433       Env.NumCorpuses = 60;
 434     else
 435       Env.NumCorpuses = 80;
 436
 437     // Continue if our crash is one of the ignored ones.
 438     if (Options.IgnoreTimeouts && ExitCode == Options.TimeoutExitCode)
 439       Env.NumTimeouts++;
 440     else if (Options.IgnoreOOMs && ExitCode == Options.OOMExitCode)
 441       Env.NumOOMs++;
 442     else if (ExitCode != 0) {
 443       Env.NumCrashes++;
 444       if (Options.IgnoreCrashes) {
 445         std::ifstream In(Job->LogPath);
 446         std::string Line;
 447         while (std::getline(In, Line, '\n'))
 448           if (Line.find("ERROR:") != Line.npos ||
 449               Line.find("runtime error:") != Line.npos)
 450             Printf("%s\n", Line.c_str());
 451       } else {
 452         // And exit if we don't ignore this crash.
 453         Printf("INFO: log from the inner process:\n%s",
 454                FileToString(Job->LogPath).c_str());
 455         StopJobs();
 456         break;
 457       }
 458     }
 459
 460     // Stop if we are over the time budget.
 461     // This is not precise, since other threads are still running
 462     // and we will wait while joining them.
 463     // We also don't stop instantly: other jobs need to finish.
 464     if (Options.MaxTotalTimeSec > 0 &&
 465         Env.secondsSinceProcessStartUp() >= (size_t)Options.MaxTotalTimeSec) {
 466       Printf("INFO: fuzzed for %zd seconds, wrapping up soon\n",
 467              Env.secondsSinceProcessStartUp());
 468       StopJobs();
 469       break;
 470     }
 471     if (Env.NumRuns >= Options.MaxNumberOfRuns) {
 472       Printf("INFO: fuzzed for %zd iterations, wrapping up soon\n",
 473              Env.NumRuns);
 474       StopJobs();
 475       break;
 476     }
 477
 478     FuzzQ.Push(Env.CreateNewJob(JobId++));
 479   }
 480
 481   for (auto &T : Threads)
 482     T.join();
 483
 484   // The workers have terminated. Don't try to remove the directory before they
 485   // terminate to avoid a race condition preventing cleanup on Windows.
 486   RmDirRecursive(Env.TempDir);
 487
 488   // Use the exit code from the last child process.
 489   Printf("INFO: exiting: %d time: %zds\n", ExitCode,
 490          Env.secondsSinceProcessStartUp());
 491   exit(ExitCode);
 492 }
 493
 494 } // namespace fuzzer