The `libfuzzer-sys` Crate

Barebones wrapper around LLVM's 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.

Usage

Use `cargo fuzz`!

Manual Usage

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 = "0.2.0"
your_crate = { path = "../path/to/your/crate" }

Change the fuzzed/src/main.rs to fuzz your code:

#![no_main]

use libfuzzer_sys::fuzz_target;

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

Build by running the following command:

$ cargo rustc -- \
    -C passes='sancov' \
    -C llvm-args='-sanitizer-coverage-level=3' \
    -Z sanitizer=address

And finally, run the fuzzer:

$ ./target/debug/fuzzed

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.

jfoote/libfuzzer