How to contribute to syzkaller

If you want to contribute to the project, feel free to send a pull request following the guidelines below.

In case this is your first pull request to syzkaller, you will need to sign Google CLA and add yourself to AUTHORS/CONTRIBUTORS files in the first commit.

What to work on

Extending/improving system call descriptions is always a good idea.

Unassigned issues from the bug tracker are worth doing, but some of them might be complicated.

To contribute code or syscall descriptions, at the very least you need to be able to build and run syzkaller, see the instructions here.

Guidelines

If you want to work on something non-trivial, please briefly describe it on the syzkaller@googlegroups.com mailing list first, so that there is an agreement on the high level approach/design and no duplication of work between contributors.

Split large changes into smaller, logically cohesive commits. Small commits are much easier and faster to review and iterate on.

Everything that can be reasonably tested should be tested.

Provide enough documentation for other users to use the new feature.

Keep the style of the code, tests, comments, docs, log/error messages consistent with the existing style.

Continuous Integration (CI) system runs a number of tests and some [opinionated] style checks. They need to pass. You can test locally with make presubmit, if you don't have some prerequisites installed, you may use syz-env (see below).

Commits

Commit messages should follow the following template:

dir/path: one-line description
<empty line>
Extended multi-line description that includes
the problem you are solving and how it is solved.

dir/path is a relative path to the main dir this commit changes (look at examples in the commit history). If several packages/dirs are significantly affected, then the following format is allowed:

dir1/path1, dir2/path2: one-line description

Though, dirs should not be included if they have only minor changes. For pervasive changes the following format is allowed:

all: one-line description

Please pay attention to punctuation. In particular:

one-line description should not start with a Capital letter.
There is no dot at the end of one-line description.
Extended multi-line description is full English sentences with Capital letters and dots.

Commit message line length is limited to 120 characters.

Also:

If your commit fixes an issue, please include Fixes #NNN line into commit message (where NNN is the issue number). This will auto-close the issue. If you need to mention an issue without closing it, add Update #NNN.
For syscall descriptions *.const files are checked-in with the *.txt changes in the same commit.

Pull requests

Rebase your working branch onto the master branch before sending a pull request to avoid merge conflicts.
Run make presubmit and ensure that it passes before sending a PR. It may require some additional packages to be installed (try sudo make install_prerequisites).
Provide a brief high-level description in the pull request title. The pull request text is mostly irrelevant, all the details should be in the commit messages.
If you're asked to add some fixes to your pull request, please squash the fixes into the old commits.

How to create a pull request on Github

First, you need an own git fork of syzkaller repository. Navigate to github.com/google/syzkaller and press Fork button in the top-right corner of the page. This will create https://github.com/YOUR_GITHUB_USERNAME/syzkaller repository.
Checkout main syzkaller repository if you have not already. The simplest way to do it is to run git clone https://github.com/google/syzkaller, this will checkout the repository in the current working directory.
Remember to export PATH=$GOPATH/bin:$PATH if you have not already.
Then add your repository as an additional origin:

shell cd syzkaller git remote add my-origin https://github.com/YOUR_GITHUB_USERNAME/syzkaller.git git fetch my-origin git checkout -b my-branch my-origin/master

This adds git origin my-origin with your repository and checks out new branch my-branch based on master branch.

Change/add files as necessary.
Commit changes locally. For this you need to run git add for all changed files, e.g. git add sys/linux/sys.txt. You can run git status to see what files were changed/created. When all files are added (git status shows no files in Changes not staged for commit section and no relevant files in Untracked files section), run git commit and enter commit description in your editor.
Run tests locally (make install_prerequisites followed by make presubmit).
Push the commit to your fork on github with git push my-origin my-branch.
Navigate to github.com/google/syzkaller and you should see green Compare & pull request button, press it. Then press Create pull request. Now your pull request should show up on pull requests page.
If you don't see Create pull request button for any reason, you can create pull request manually. For that navigate to pull requests page, press New pull request, then compare across forks and choose google/syzkaller/master as base and YOUR_GITHUB_USERNAME/syzkaller/my-branch as compare and press Create pull request.
If you decided to rebase commits in my-branch (e.g. to rebase them onto updated master) after you created a pull-request, you will need to do a force push: git push -f my-origin my-branch.

Using syz-env

Developing syzkaller requires a number of tools installed (Go toolchain, C/C++ cross-compilers, golangci-lint, etc). Installing all of them may be cumbersome, e.g. due broken/missing packages. syz-env provides a working hermetic development environment based on a Docker container. If you don't yet have Docker installed, see documentation, in particular regarding enabling sudo-less Docker (Googlers see go/docker).

It's recommended to create an alias for syz-env script:

alias syz-env="$(go env GOPATH)/src/github.com/google/syzkaller/tools/syz-env"

Then it can be used to wrap almost any make invocation as:

syz-env make format
syz-env make presubmit
syz-env make extract SOURCEDIR=$(readlink -f ~/linux)

Or other commands/scripts, e.g.:

syz-env go test -short ./pkg/csource

Or you may run the shell inside of the container with just syz-env and look around.

To update syz-env container to the latest version do:

docker pull gcr.io/syzkaller/env

You can also build the container from the respective Dockerfile by setting the SYZ_ENV_BUILD environment variable, i.e.:

SYZ_ENV_BUILD=1 syz-env

This can be useful to test local changes that have not been pushed to the registry yet.

Using act

.github/workflows has more tests compared to syz-env make presubmit. To have the same tests as the workflow, we can run these workflow jobs locally.

# install act
make act
# list all jobs
bin/act -l
# run all jobs
bin/act
# run job with name build
bin/act -j build