12-custom-mutator-fail.patch

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# HG changeset patch

# User Christian Holler <choller@mozilla.com>

# Date 1596126768 -7200

#      Thu Jul 30 18:32:48 2020 +0200

# Node ID 64e7d096fa77a62b71a306b2c5383b8f75ac4945

# Parent  ea198a0331a6db043cb5978512226977514104db

[libFuzzer] Allow custom mutators to fail

diff --git a/FuzzerLoop.cpp b/FuzzerLoop.cpp

--- a/FuzzerLoop.cpp

+++ b/FuzzerLoop.cpp

@@ -690,16 +690,20 @@ void Fuzzer::MutateAndTestOne() {

     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);

+    if (!NewSize)

+      continue;

     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,

@@ -850,17 +854,19 @@ void Fuzzer::Loop(Vector<SizedFile> &Cor

 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);

+      assert(NewSize <= MaxMutationLen);

+      if (!NewSize)

+        continue;

       ExecuteCallback(CurrentUnitData, NewSize);

       PrintPulseAndReportSlowInput(CurrentUnitData, NewSize);

       TryDetectingAMemoryLeak(CurrentUnitData, NewSize,

                               /*DuringInitialCorpusExecution*/ false);