Segfault when calling `index.AddAll`

[pjbgf]

We have experienced index.AddAll causing segfaults. The exact same code depending on the machine it is running on and the repository it is adding files to, may consistently result in a segfault from a background thread: signal: segmentation fault (core dumped).

In other cases, it may not happen as consistently or not happen at all. The code extract below is what led to the segfault:

    var parentC []*libgit2.Commit
    head, err := headCommit(repo)
    if err == nil {
        defer head.Free()
        parentC = append(parentC, head)
    }

    index, err := repo.Index()
    if err != nil {
        return "", err
    }
    defer index.Free()

    tracelog.Info("adding files to index")
    c := 1
    err = index.AddAll(nil, libgit2.IndexAddDefault, func(s1, s2 string) error {
        tracelog.Info("adding file", "name", s1, "count", c)
        c += 1
        return nil
    })
    if err != nil {
        return "", err
    }
    tracelog.Info("added files to index")

https://github.com/fluxcd/image-automation-controller/blob/235edabafd1ce34c15635d6c6b5aea18d298a4d3/controllers/imageupdateautomation_controller.go#L627

Versions:

• github.com/libgit2/git2go/v33 v33.0.9
• libgit2 v1.3.1

Relates to https://github.com/fluxcd/image-automation-controller/issues/339