go-fuzz-headers

This repository contains various helper functions for go fuzzing. It is mostly used in combination with go-fuzz, but compatibility with fuzzing in the standard library will also be supported. Any coverage guided fuzzing engine that provides an array or slice of bytes can be used with go-fuzz-headers.

Usage

Using go-fuzz-headers is easy. First create a new consumer with the bytes provided by the fuzzing engine:

import (
	fuzz "github.com/AdaLogics/go-fuzz-headers"
)
data := []byte{'R', 'a', 'n', 'd', 'o', 'm'}
f := fuzz.NewConsumer(data)

This creates a Consumer that consumes the bytes of the input as it uses them to fuzz different types.

After that, f can be used to easily create fuzzed instances of different types. Below are some examples:

Structs

One of the most useful features of go-fuzz-headers is its ability to fill structs with the data provided by the fuzzing engine. This is done with a single line:

type Person struct {
    Name string
    Age  int
}
p := Person{}
// Fill p with values based on the data provided by the fuzzing engine:
err := f.GenerateStruct(&p)

This includes nested structs too. In this example, the fuzz Consumer will also insert values in p.BestFriend:

type PersonI struct {
    Name       string
    Age        int
    BestFriend PersonII
}
type PersonII struct {
    Name string
    Age  int
}
p := PersonI{}
err := f.GenerateStruct(&p)

If the consumer should insert values for unexported fields as well as exported, this can be enabled with:

f.AllowUnexportedFields()

...and disabled with:

f.DisallowUnexportedFields()

Other types:

Other useful APIs:

createdString, err := f.GetString() // Gets a string
createdInt, err := f.GetInt() // Gets an integer
createdByte, err := f.GetByte() // Gets a byte
createdBytes, err := f.GetBytes() // Gets a byte slice
createdBool, err := f.GetBool() // Gets a boolean
err := f.FuzzMap(target_map) // Fills a map
createdTarBytes, err := f.TarBytes() // Gets bytes of a valid tar archive
err := f.CreateFiles(inThisDir) // Fills inThisDir with files
createdString, err := f.GetStringFrom("anyCharInThisString", ofThisLength) // Gets a string that consists of chars from "anyCharInThisString" and has the exact length "ofThisLength"

Most APIs are added as they are needed.

Projects that use go-fuzz-headers

• runC
• Istio
• Vitess
• Containerd

Feel free to add your own project to the list, if you use go-fuzz-headers to fuzz it.

Status

The project is under development and will be updated regularly.

References

go-fuzz-headers' approach to fuzzing structs is strongly inspired by gofuzz.