Re: [REGRESSION v3.14-rc2] NULL dereference in icmp6_send()

From: Hannes Frederic Sowa
Date: Mon Feb 17 2014 - 13:51:02 EST


Hi!

On Mon, Feb 17, 2014 at 01:46:13PM -0500, Theodore Ts'o wrote:
> I was sitting in the Admiral's Club of Boston Logan airport, having
> connected to the free airport wifi, although I had not yet logged into
> the captive portal, when I received the following BUG. I've also seen
> this once before when connected to my home network (running the CeroWRT
> stable snapshot, versoin 3.7.5-2), although I wasn't able to get a
> screen shot that time:
>
> https://plus.google.com/photos/+TheodoreTso/albums/5981437894092747105/5981437896646076466
>
> The transcribed stack dump is:
>
> icmp6_send
> ip6_expire_frag_queue
> ip6_frag_expire
> call_timer_fn
> run_timer_softirq
> irq_exit
> ...
>
> I was running v3.13 and v3.13-rcX previously without seeing this, so I
> suspect this is a regression.

At that point the skb does not have a dst attached, so we panic in
icmp6_send.

This is fixed here:
https://git.kernel.org/cgit/linux/kernel/git/davem/net.git/commit/?id=d94c1f92bbf2c42c5febd68bbea51fffeac90834

Greetings,

Hannes

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