GHSA-hpcg-xjq5-g666: Minder affected by denial of service from maliciously configured Git repository

Minder’s Git provider is vulnerable to a denial of service from a maliciously configured GitHub repository. The Git provider clones users repositories using the github.com/go-git/go-git/v5 library on these lines:

https://github.com/stacklok/minder/blob/85985445c8ac3e51f03372e99c7b2f08a6d274aa/internal/providers/git/git.go#L55-L89

The Git provider does the following on these lines:

First, it sets the CloneOptions, specifying the url, the depth etc:

https://github.com/stacklok/minder/blob/85985445c8ac3e51f03372e99c7b2f08a6d274aa/internal/providers/git/git.go#L56-L62

It then validates the options:

https://github.com/stacklok/minder/blob/85985445c8ac3e51f03372e99c7b2f08a6d274aa/internal/providers/git/git.go#L66-L68

It then sets up an in-memory filesystem, to which it clones:

https://github.com/stacklok/minder/blob/85985445c8ac3e51f03372e99c7b2f08a6d274aa/internal/providers/git/git.go#L70-L71

Finally, it clones the repository:

https://github.com/stacklok/minder/blob/85985445c8ac3e51f03372e99c7b2f08a6d274aa/internal/providers/git/git.go#L77

This (g *Git) Clone() method is vulnerable to a DoS attack: A Minder user can instruct Minder to clone a large repository which will exhaust memory and crash the Minder server. The root cause of this vulnerability is a combination of the following conditions:

1. Users can control the Git URL which Minder clones.
2. Minder does not enforce a size limit to the repository.
3. Minder clones the entire repository into memory.