From: Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH] xfrm: fix xfrm_input/xfrm_tunnel_check oops
Date: Tue, 7 Apr 2015 14:43:41 +0300
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 <20150407085731.GH20559@secunet.com>
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To: Steffen Klassert <steffen.klassert@secunet.com>
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On Tue, Apr 07, 2015 at 10:57:32AM +0200, Steffen Klassert wrote:
> On Thu, Apr 02, 2015 at 10:58:24AM +0300, Alexey Dobriyan wrote:
> > https://bugzilla.kernel.org/show_bug.cgi?id=95211
> > 
> > Commit 70be6c91c86596ad2b60c73587880b47df170a41
> > ("xfrm: Add xfrm_tunnel_skb_cb to the skb common buffer") added check
> > which dereferences ->outer_mode too early but larval SAs don't have
> > this pointer set (yet). So check for tunnel stuff later.
> > 
> > Mike Noordermeer reported this bug and patiently applied all the debugging.
> > 
> > Technically this is remote-oops-in-interrupt-context type of thing.
> > 
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000034
> > IP: [<ffffffff8150dca2>] xfrm_input+0x3c2/0x5a0
> > 	...
> > [<ffffffff81500fc6>] ? xfrm4_esp_rcv+0x36/0x70
> > [<ffffffff814acc9a>] ? ip_local_deliver_finish+0x9a/0x200
> > [<ffffffff81471b83>] ? __netif_receive_skb_core+0x6f3/0x8f0
> > 	...
> > 
> > RIP  [<ffffffff8150dca2>] xfrm_input+0x3c2/0x5a0
> > Kernel panic - not syncing: Fatal exception in interrupt
> > 
> > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> 
> Good catch!
> 
> Applied to the ipsec tree, thanks everyone!

For the record Mike confirmed that the patch works:
https://bugzilla.kernel.org/show_bug.cgi?id=95211#c20