Re: net: GPF in eth_header

From: Eric Dumazet
Date: Mon Nov 28 2016 - 14:48:53 EST


On Mon, 2016-11-28 at 20:34 +0100, Dmitry Vyukov wrote:
> On Mon, Nov 28, 2016 at 8:04 PM, 'Andrey Konovalov' via syzkaller

> > Hi Eric,
> >
> > As far as I can see, skb_network_offset() becomes negative after
> > pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data) in nf_ct_frag6_queue().
> > At least I'm able to detect that with a BUG_ON().
> >
> > Also it seems that the issue is only reproducible (at least with the
> > poc I provided) for a short time after boot.
>
>
> Eric,
>
> Is it enough to debug? Or maybe Andrey can trace some values for you.

Well, now we are talking, if you tell me how many modules you load, it
might help ;)

nf_ct_frag6_queue is nowhere to be seen in my kernels, that might
explain why I could not reproduce the bug.

Let me try ;)