Clone this repo:
  1. 679b602 Update README.md by Kostya Serebryany · 2 weeks ago master
  2. a9fb4da Add links to known bug reports and fuzzers which use this library by Vitaly Buka · 4 weeks ago
  3. 7853387 added missing newlines to two CMakeLists.txt files by Christian Hartlage · 8 weeks ago
  4. add10cd surrounded modifications to the "check" target with tests for LIB_PROTO_MUTATOR_TESTING by Christian Hartlage · 8 weeks ago
  5. 5e55787 Add install to the Travis test and install docs. by Allen Webb · 8 weeks ago

libprotobuf-mutator

Overview

libprotobuf-mutator is a library to randomly mutate protobuffers.
It could be used together with guided fuzzing engines, such as libFuzzer.

Quick start on Debian/Ubuntu

Install prerequisites:

sudo apt-get update
sudo apt-get install binutils cmake ninja-build liblzma-dev libz-dev pkg-config

Compile and test everything:

mkdir build
cd build
cmake .. -GNinja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Debug
ninja check

Clang is only needed for libFuzzer integration.
By default, the system-installed version of protobuf is used. However, on some systems, the system version is too old. You can pass LIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=ON to cmake to automatically download and build a working version of protobuf.

Installation:

ninja
sudo ninja install

This installs the headers, pkg-config, and static library. By default the headers are put in /usr/local/include/libprotobuf-mutator.

Usage

To use libprotobuf-mutator simply include mutator.h and mutator.cc into your build files.

The ProtobufMutator class implements mutations of the protobuf tree structure and mutations of individual fields. The field mutation logic is very basic -- for better results you should override the ProtobufMutator::Mutate* methods with more sophisticated logic, e.g. using libFuzzer's mutators.

To apply one mutation to a protobuf object do the following:

class MyProtobufMutator : public protobuf_mutator::Mutator {
 public:
  MyProtobufMutator(uint32_t seed) : protobuf_mutator::Mutator(seed) {}
  // Optionally redefine the Mutate* methods to perform more sophisticated mutations.
}
void Mutate(MyMessage* message) {
  MyProtobufMutator mutator(my_random_seed);
  mutator.Mutate(message, 200);
}

See also the ProtobufMutatorMessagesTest.UsageExample test from mutator_test.cc.

Integrating with libFuzzer

LibFuzzerProtobufMutator can help to integrate with libFuzzer. For example

#include "src/libfuzzer/libfuzzer_macro.h"

DEFINE_PROTO_FUZZER(const MyMessageType& input) {
  // Code which needs to be fuzzed.
  ConsumeMyMessageType(input);
}

Please see libfuzzer_example.cc as an example.

UTF-8 strings

“proto2” and “proto3” handle invalid UTF-8 strings differently. In both cases string should be UTF-8, however only “proto3” enforces that. So if fuzzer is applied to “proto2” type libprotobuf-mutator will generate any strings including invalid UTF-8. If it's a “proto3” message type, only valid UTF-8 will be used.

Users of the library

Bugs found with help of the library

Chromium

Envoy

Related materials