Re: [PATCH bpf] bpf: fix OOB read when printing XDP link fdinfo

[Lorenz Bauer]

On Fri, 16 Jul 2021 at 21:44, Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
>
> Well, oops. Thanks for the fix!
>
> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
>
> It would be great to have a compilation error for something like this.
> I wonder if we can do something to detect this going forward?

I had a second patch that introduced MAX_BPF_LINK_TYPE, etc. and then
added explicit array initializers:

     [MAX_BPF_LINK_TYPE] = NULL,

That turns the OOB read into a NULL read. But it has to be done for
every inclusion of bpf_types.h so it's
a bit cumbersome. Maybe add MAX_BPF_LINK_TYPE and then add an entry in
bpf_types.h for it as well?

--
Lorenz Bauer  |  Systems Engineer
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