On Thu, Feb 11, 2021 at 4:59 PM Yonghong Song <yhs@xxxxxx> wrote:
>
> Commit 15d83c4d7cef ("bpf: Allow loading of a bpf_iter program")
> cached btf_id in struct bpf_iter_target_info so later on
> if it can be checked cheaply compared to checking registered names.
>
> syzbot found a bug that uninitialized value may occur to
> bpf_iter_target_info->btf_id. This is because we allocated
> bpf_iter_target_info structure with kmalloc and never initialized
> field btf_id afterwards. This uninitialized btf_id is typically
> compared to a u32 bpf program func proto btf_id, and the chance
> of being equal is extremely slim.
>
> This patch fixed the issue by using kzalloc which will also
> prevent future likely instances due to adding new fields.
>
> Reported-by: syzbot+580f4f2a272e452d55cb@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 15d83c4d7cef ("bpf: Allow loading of a bpf_iter program")
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
Though it's a fix it's too late in the cycle.
I've applied to bpf-next.
