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

On Fri, 16 Jul 2021 at 21:44, Andrii Nakryiko [off-list ref] wrote:

Well, oops. Thanks for the fix!

Acked-by: Andrii Nakryiko <andrii@kernel.org>

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
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK

www.cloudflare.com