1 files changed, 427 insertions, 0 deletions

diff --git a/tools/fuzzing/libfuzzer/FuzzerFork.cpp b/tools/fuzzing/libfuzzer/FuzzerFork.cpp
new file mode 100644
index 0000000000..ee2a99a250
--- /dev/null
+++ b/tools/fuzzing/libfuzzer/FuzzerFork.cpp
@@ -0,0 +1,427 @@
+//===- FuzzerFork.cpp - run fuzzing in separate subprocesses --------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+// Spawn and orchestrate separate fuzzing processes.
+//===----------------------------------------------------------------------===//
+
+#include "FuzzerCommand.h"
+#include "FuzzerFork.h"
+#include "FuzzerIO.h"
+#include "FuzzerInternal.h"
+#include "FuzzerMerge.h"
+#include "FuzzerSHA1.h"
+#include "FuzzerTracePC.h"
+#include "FuzzerUtil.h"
+
+#include <atomic>
+#include <chrono>
+#include <condition_variable>
+#include <fstream>
+#include <memory>
+#include <mutex>
+#include <queue>
+#include <sstream>
+#include <thread>
+
+namespace fuzzer {
+
+struct Stats {
+  size_t number_of_executed_units = 0;
+  size_t peak_rss_mb = 0;
+  size_t average_exec_per_sec = 0;
+};
+
+static Stats ParseFinalStatsFromLog(const std::string &LogPath) {
+  std::ifstream In(LogPath);
+  std::string Line;
+  Stats Res;
+  struct {
+    const char *Name;
+    size_t *Var;
+  } NameVarPairs[] = {
+      {"stat::number_of_executed_units:", &Res.number_of_executed_units},
+      {"stat::peak_rss_mb:", &Res.peak_rss_mb},
+      {"stat::average_exec_per_sec:", &Res.average_exec_per_sec},
+      {nullptr, nullptr},
+  };
+  while (std::getline(In, Line, '\n')) {
+    if (Line.find("stat::") != 0) continue;
+    std::istringstream ISS(Line);
+    std::string Name;
+    size_t Val;
+    ISS >> Name >> Val;
+    for (size_t i = 0; NameVarPairs[i].Name; i++)
+      if (Name == NameVarPairs[i].Name)
+        *NameVarPairs[i].Var = Val;
+  }
+  return Res;
+}
+
+struct FuzzJob {
+  // Inputs.
+  Command Cmd;
+  std::string CorpusDir;
+  std::string FeaturesDir;
+  std::string LogPath;
+  std::string SeedListPath;
+  std::string CFPath;
+  size_t      JobId;
+
+  int         DftTimeInSeconds = 0;
+
+  // Fuzzing Outputs.
+  int ExitCode;
+
+  ~FuzzJob() {
+    RemoveFile(CFPath);
+    RemoveFile(LogPath);
+    RemoveFile(SeedListPath);
+    RmDirRecursive(CorpusDir);
+    RmDirRecursive(FeaturesDir);
+  }
+};
+
+struct GlobalEnv {
+  Vector<std::string> Args;
+  Vector<std::string> CorpusDirs;
+  std::string MainCorpusDir;
+  std::string TempDir;
+  std::string DFTDir;
+  std::string DataFlowBinary;
+  Set<uint32_t> Features, Cov;
+  Set<std::string> FilesWithDFT;
+  Vector<std::string> Files;
+  Random *Rand;
+  std::chrono::system_clock::time_point ProcessStartTime;
+  int Verbosity = 0;
+
+  size_t NumTimeouts = 0;
+  size_t NumOOMs = 0;
+  size_t NumCrashes = 0;
+
+
+  size_t NumRuns = 0;
+
+  std::string StopFile() { return DirPlusFile(TempDir, "STOP"); }
+
+  size_t secondsSinceProcessStartUp() const {
+    return std::chrono::duration_cast<std::chrono::seconds>(
+               std::chrono::system_clock::now() - ProcessStartTime)
+        .count();
+  }
+
+  FuzzJob *CreateNewJob(size_t JobId) {
+    Command Cmd(Args);
+    Cmd.removeFlag("fork");
+    Cmd.removeFlag("runs");
+    Cmd.removeFlag("collect_data_flow");
+    for (auto &C : CorpusDirs) // Remove all corpora from the args.
+      Cmd.removeArgument(C);
+    Cmd.addFlag("reload", "0");  // working in an isolated dir, no reload.
+    Cmd.addFlag("print_final_stats", "1");
+    Cmd.addFlag("print_funcs", "0");  // no need to spend time symbolizing.
+    Cmd.addFlag("max_total_time", std::to_string(std::min((size_t)300, JobId)));
+    Cmd.addFlag("stop_file", StopFile());
+    if (!DataFlowBinary.empty()) {
+      Cmd.addFlag("data_flow_trace", DFTDir);
+      if (!Cmd.hasFlag("focus_function"))
+        Cmd.addFlag("focus_function", "auto");
+    }
+    auto Job = new FuzzJob;
+    std::string Seeds;
+    if (size_t CorpusSubsetSize =
+            std::min(Files.size(), (size_t)sqrt(Files.size() + 2))) {
+      auto Time1 = std::chrono::system_clock::now();
+      for (size_t i = 0; i < CorpusSubsetSize; i++) {
+        auto &SF = Files[Rand->SkewTowardsLast(Files.size())];
+        Seeds += (Seeds.empty() ? "" : ",") + SF;
+        CollectDFT(SF);
+      }
+      auto Time2 = std::chrono::system_clock::now();
+      Job->DftTimeInSeconds = duration_cast<seconds>(Time2 - Time1).count();
+    }
+    if (!Seeds.empty()) {
+      Job->SeedListPath =
+          DirPlusFile(TempDir, std::to_string(JobId) + ".seeds");
+      WriteToFile(Seeds, Job->SeedListPath);
+      Cmd.addFlag("seed_inputs", "@" + Job->SeedListPath);
+    }
+    Job->LogPath = DirPlusFile(TempDir, std::to_string(JobId) + ".log");
+    Job->CorpusDir = DirPlusFile(TempDir, "C" + std::to_string(JobId));
+    Job->FeaturesDir = DirPlusFile(TempDir, "F" + std::to_string(JobId));
+    Job->CFPath = DirPlusFile(TempDir, std::to_string(JobId) + ".merge");
+    Job->JobId = JobId;
+
+
+    Cmd.addArgument(Job->CorpusDir);
+    Cmd.addFlag("features_dir", Job->FeaturesDir);
+
+    for (auto &D : {Job->CorpusDir, Job->FeaturesDir}) {
+      RmDirRecursive(D);
+      MkDir(D);
+    }
+
+    Cmd.setOutputFile(Job->LogPath);
+    Cmd.combineOutAndErr();
+
+    Job->Cmd = Cmd;
+
+    if (Verbosity >= 2)
+      Printf("Job %zd/%p Created: %s\n", JobId, Job,
+             Job->Cmd.toString().c_str());
+    // Start from very short runs and gradually increase them.
+    return Job;
+  }
+
+  int RunOneMergeJob(FuzzJob *Job) {
+    auto Stats = ParseFinalStatsFromLog(Job->LogPath);
+    NumRuns += Stats.number_of_executed_units;
+
+    Vector<SizedFile> TempFiles, MergeCandidates;
+    // Read all newly created inputs and their feature sets.
+    // Choose only those inputs that have new features.
+    int Res = GetSizedFilesFromDir(Job->CorpusDir, &TempFiles);
+    if (Res != 0)
+      return Res;
+    std::sort(TempFiles.begin(), TempFiles.end());
+    for (auto &F : TempFiles) {
+      auto FeatureFile = F.File;
+      FeatureFile.replace(0, Job->CorpusDir.size(), Job->FeaturesDir);
+      auto FeatureBytes = FileToVector(FeatureFile, 0, false);
+      assert((FeatureBytes.size() % sizeof(uint32_t)) == 0);
+      Vector<uint32_t> NewFeatures(FeatureBytes.size() / sizeof(uint32_t));
+      memcpy(NewFeatures.data(), FeatureBytes.data(), FeatureBytes.size());
+      for (auto Ft : NewFeatures) {
+        if (!Features.count(Ft)) {
+          MergeCandidates.push_back(F);
+          break;
+        }
+      }
+    }
+    // if (!FilesToAdd.empty() || Job->ExitCode != 0)
+    Printf("#%zd: cov: %zd ft: %zd corp: %zd exec/s %zd "
+           "oom/timeout/crash: %zd/%zd/%zd time: %zds job: %zd dft_time: %d\n",
+           NumRuns, Cov.size(), Features.size(), Files.size(),
+           Stats.average_exec_per_sec, NumOOMs, NumTimeouts, NumCrashes,
+           secondsSinceProcessStartUp(), Job->JobId, Job->DftTimeInSeconds);
+
+    if (MergeCandidates.empty()) return 0;
+
+    Vector<std::string> FilesToAdd;
+    Set<uint32_t> NewFeatures, NewCov;
+    CrashResistantMerge(Args, {}, MergeCandidates, &FilesToAdd, Features,
+                        &NewFeatures, Cov, &NewCov, Job->CFPath, false);
+    if (Fuzzer::isGracefulExitRequested())
+      return 0;
+    for (auto &Path : FilesToAdd) {
+      auto U = FileToVector(Path);
+      auto NewPath = DirPlusFile(MainCorpusDir, Hash(U));
+      WriteToFile(U, NewPath);
+      Files.push_back(NewPath);
+    }
+    Features.insert(NewFeatures.begin(), NewFeatures.end());
+    Cov.insert(NewCov.begin(), NewCov.end());
+    for (auto Idx : NewCov)
+      if (auto *TE = TPC.PCTableEntryByIdx(Idx))
+        if (TPC.PcIsFuncEntry(TE))
+          PrintPC("  NEW_FUNC: %p %F %L\n", "",
+                  TPC.GetNextInstructionPc(TE->PC));
+    return 0;
+  }
+
+
+  void CollectDFT(const std::string &InputPath) {
+    if (DataFlowBinary.empty()) return;
+    if (!FilesWithDFT.insert(InputPath).second) return;
+    Command Cmd(Args);
+    Cmd.removeFlag("fork");
+    Cmd.removeFlag("runs");
+    Cmd.addFlag("data_flow_trace", DFTDir);
+    Cmd.addArgument(InputPath);
+    for (auto &C : CorpusDirs) // Remove all corpora from the args.
+      Cmd.removeArgument(C);
+    Cmd.setOutputFile(DirPlusFile(TempDir, "dft.log"));
+    Cmd.combineOutAndErr();
+    // Printf("CollectDFT: %s\n", Cmd.toString().c_str());
+    ExecuteCommand(Cmd);
+  }
+
+};
+
+struct JobQueue {
+  std::queue<FuzzJob *> Qu;
+  std::mutex Mu;
+  std::condition_variable Cv;
+
+  void Push(FuzzJob *Job) {
+    {
+      std::lock_guard<std::mutex> Lock(Mu);
+      Qu.push(Job);
+    }
+    Cv.notify_one();
+  }
+  FuzzJob *Pop() {
+    std::unique_lock<std::mutex> Lk(Mu);
+    // std::lock_guard<std::mutex> Lock(Mu);
+    Cv.wait(Lk, [&]{return !Qu.empty();});
+    assert(!Qu.empty());
+    auto Job = Qu.front();
+    Qu.pop();
+    return Job;
+  }
+};
+
+void WorkerThread(JobQueue *FuzzQ, JobQueue *MergeQ) {
+  while (auto Job = FuzzQ->Pop()) {
+    // Printf("WorkerThread: job %p\n", Job);
+    Job->ExitCode = ExecuteCommand(Job->Cmd);
+    MergeQ->Push(Job);
+  }
+}
+
+// This is just a skeleton of an experimental -fork=1 feature.
+int FuzzWithFork(Random &Rand, const FuzzingOptions &Options,
+                  const Vector<std::string> &Args,
+                  const Vector<std::string> &CorpusDirs, int NumJobs) {
+  Printf("INFO: -fork=%d: fuzzing in separate process(s)\n", NumJobs);
+
+  GlobalEnv Env;
+  Env.Args = Args;
+  Env.CorpusDirs = CorpusDirs;
+  Env.Rand = &Rand;
+  Env.Verbosity = Options.Verbosity;
+  Env.ProcessStartTime = std::chrono::system_clock::now();
+  Env.DataFlowBinary = Options.CollectDataFlow;
+
+  Vector<SizedFile> SeedFiles;
+  int Res;
+  for (auto &Dir : CorpusDirs) {
+    Res = GetSizedFilesFromDir(Dir, &SeedFiles);
+    if (Res != 0)
+      return Res;
+  }
+  std::sort(SeedFiles.begin(), SeedFiles.end());
+  Env.TempDir = TempPath("FuzzWithFork", ".dir");
+  Env.DFTDir = DirPlusFile(Env.TempDir, "DFT");
+  RmDirRecursive(Env.TempDir);  // in case there is a leftover from old runs.
+  MkDir(Env.TempDir);
+  MkDir(Env.DFTDir);
+
+
+  if (CorpusDirs.empty())
+    MkDir(Env.MainCorpusDir = DirPlusFile(Env.TempDir, "C"));
+  else
+    Env.MainCorpusDir = CorpusDirs[0];
+
+  auto CFPath = DirPlusFile(Env.TempDir, "merge.txt");
+  Res = CrashResistantMerge(Env.Args, {}, SeedFiles, &Env.Files, {}, &Env.Features,
+                      {}, &Env.Cov,
+                      CFPath, false);
+  if (Res != 0)
+    return Res;
+  if (Fuzzer::isGracefulExitRequested())
+    return 0;
+
+  RemoveFile(CFPath);
+  Printf("INFO: -fork=%d: %zd seed inputs, starting to fuzz in %s\n", NumJobs,
+         Env.Files.size(), Env.TempDir.c_str());
+
+  int ExitCode = 0;
+
+  JobQueue FuzzQ, MergeQ;
+
+  auto StopJobs = [&]() {
+    for (int i = 0; i < NumJobs; i++)
+      FuzzQ.Push(nullptr);
+    MergeQ.Push(nullptr);
+    WriteToFile(Unit({1}), Env.StopFile());
+  };
+
+  size_t JobId = 1;
+  Vector<std::thread> Threads;
+  for (int t = 0; t < NumJobs; t++) {
+    Threads.push_back(std::thread(WorkerThread, &FuzzQ, &MergeQ));
+    FuzzQ.Push(Env.CreateNewJob(JobId++));
+  }
+
+  while (true) {
+    std::unique_ptr<FuzzJob> Job(MergeQ.Pop());
+    if (!Job)
+      break;
+    ExitCode = Job->ExitCode;
+    if (ExitCode == Options.InterruptExitCode) {
+      Printf("==%lu== libFuzzer: a child was interrupted; exiting\n", GetPid());
+      StopJobs();
+      break;
+    }
+    if (Fuzzer::MaybeExitGracefully())
+      return 0;
+
+    Res = Env.RunOneMergeJob(Job.get());
+    if (Res != 0)
+      return Res;
+    if (Fuzzer::isGracefulExitRequested())
+      return 0;
+
+    // Continue if our crash is one of the ignorred ones.
+    if (Options.IgnoreTimeouts && ExitCode == Options.TimeoutExitCode)
+      Env.NumTimeouts++;
+    else if (Options.IgnoreOOMs && ExitCode == Options.OOMExitCode)
+      Env.NumOOMs++;
+    else if (ExitCode != 0) {
+      Env.NumCrashes++;
+      if (Options.IgnoreCrashes) {
+        std::ifstream In(Job->LogPath);
+        std::string Line;
+        while (std::getline(In, Line, '\n'))
+          if (Line.find("ERROR:") != Line.npos ||
+              Line.find("runtime error:") != Line.npos)
+            Printf("%s\n", Line.c_str());
+      } else {
+        // And exit if we don't ignore this crash.
+        Printf("INFO: log from the inner process:\n%s",
+               FileToString(Job->LogPath).c_str());
+        StopJobs();
+        break;
+      }
+    }
+
+    // Stop if we are over the time budget.
+    // This is not precise, since other threads are still running
+    // and we will wait while joining them.
+    // We also don't stop instantly: other jobs need to finish.
+    if (Options.MaxTotalTimeSec > 0 &&
+        Env.secondsSinceProcessStartUp() >= (size_t)Options.MaxTotalTimeSec) {
+      Printf("INFO: fuzzed for %zd seconds, wrapping up soon\n",
+             Env.secondsSinceProcessStartUp());
+      StopJobs();
+      break;
+    }
+    if (Env.NumRuns >= Options.MaxNumberOfRuns) {
+      Printf("INFO: fuzzed for %zd iterations, wrapping up soon\n",
+             Env.NumRuns);
+      StopJobs();
+      break;
+    }
+
+    FuzzQ.Push(Env.CreateNewJob(JobId++));
+  }
+
+  for (auto &T : Threads)
+    T.join();
+
+  // The workers have terminated. Don't try to remove the directory before they
+  // terminate to avoid a race condition preventing cleanup on Windows.
+  RmDirRecursive(Env.TempDir);
+
+  // Use the exit code from the last child process.
+  Printf("INFO: exiting: %d time: %zds\n", ExitCode,
+         Env.secondsSinceProcessStartUp());
+  return ExitCode;
+}
+
+} // namespace fuzzer