Re: Bug#10954: Kernel panic: skpush:under (fwd)

Jason Flynn 605619 (flynnjs@mobile-systems.bt.co.uk)
Wed, 02 Jul 1997 08:27:33 +0000

Eric.Schenk@dna.lth.se wrote:
>
> Phil Karn <karn@ka9q.ampr.org> writes:
> >This morning my machine panicked with the following on the console:
> >
> >Kernel panic: skpush:under: 0014140c:84772916
> >In swapper task - not syncing
> >
> >According to my symbol table and my reading of the source code, this
> >came from a call to skb_push() from within packet_rcv(). packet_rcv
> >is at 001413c8 and packet_sendmsg is at 00141484.
>
> This indicates that either some device driver blew it when
> setting up the ethernet headers on an incoming packet.
>
> >The machine has two Ethernet interfaces, a 3C590 and a NE2000.
> >It's used as an IP router with a fairly complex configuration; both
> >IP masquerading and IP-in-IP tunneling are used. At the time of
> >the crash I had tcpdump running on the NE2000 interface.
>
> Can you give me a bit more information about this setup?
>
> My first guess is that the tunneling code is the culprit,
> but it's a bit late for me to go digging yet tonight.

I've seen this happen quite a bit after a fragmented packet is
re-assembled and put through the de-tunneler and then passed back
down to be 're-received'. This is especially the case when bridging
was in the mix too. I sent a patch to Alan to fix this with the
bridging for 2.0 a couple of months ago.
- It looks like a similar problem here.

J