Barebones wrapper around libFuzzer runtime library.

The CPP parts are extracted from compiler-rt git repository with git filter-branch.

libFuzzer relies on LLVM sanitizer support. The Rust compiler has built-in support for LLVM sanitizer support, for now, it's limited to Linux. As a result, libfuzzer-sys only works on Linux.

How to use

Use cargo-fuzz.

This crate can also be used manually as following:

First create a new cargo project:

$ cargo new --bin fuzzed
$ cd fuzzed

Then add a dependency on the fuzzer-sys crate and your own crate:

[dependencies]
libfuzzer-sys = { git = "https://github.com/rust-fuzz/libfuzzer-sys.git" } # will eventually publish to crates.io
your_crate = "*" # or something

and change the src/main.rs to fuzz your code:

#![no_main]

#[macro_use]
extern crate libfuzzer_sys;
extern crate your_crate;

fuzz_target!(|data: &[u8]| {
    // code to fuzz goes here
});

Finally, run the following commands:

$ cargo rustc -- -C passes='sancov' -C llvm-args='-sanitizer-coverage-level=3' -Z sanitizer=address
$ ./target/debug/fuzzed # runs fuzzing

Updating libfuzzer from upstream

./update-libfuzzer.sh <llvm/compiler-rt SHA1>

License

All files in libfuzzer directory are licensed NCSA. Everything else is dual-licensed Apache 2.0 and MIT.