linux-kernel - Re: NULL pointer dereference in selinux_ip_postroute

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Date:	Tue, 7 Aug 2012 18:01:38 -0400
From:	Paul Moore <paul@...l-moore.com>
To:	John Stultz <john.stultz@...aro.org>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	James Morris <james.l.morris@...cle.com>, selinux@...ho.nsa.gov
Subject: Re: NULL pointer dereference in selinux_ip_postroute_compat

On Tue, Aug 7, 2012 at 5:58 PM, John Stultz <john.stultz@...aro.org> wrote:
> On 08/07/2012 02:50 PM, Paul Moore wrote:
>>
>> On Tue, Aug 7, 2012 at 2:12 PM, John Stultz <john.stultz@...aro.org>
>> wrote:
>>>
>>> Hi,
>>>      With my kvm environment using 3.6-rc1+, I'm seeing NULL pointer
>>> dereferences in selinux_ip_postroute_compat(). It looks like the sksec
>>> value
>>> is null and we die in the following line:
>>>
>>>      if (selinux_xfrm_postroute_last(sksec->sid, skb, &ad, proto))
>>>
>>> This triggers every time I shutdown the machine, but has also triggered
>>> randomly after a few hours.
>>>
>>> This is on an ubuntu 12.04 image, not using selinux.
>>
>> NOTE: Adding the SELinux list to the CC line
>
> Thanks!
>
>> Hi,
>>
>> I'm trying to understand this and I was hoping you could you clarify a
>> few things for me:
>>
>> * Is the panic in the Ubuntu 12.04 guest, or the host?  If the host,
>> could you share what distribution you are using?
>
> Sorry, its a 12.04 guest.  I think the host is Ubuntu 12.04 as well.
>
>
>> * When you say you are not using SELinux, could you be more specific?
>> It seems odd that you are not using SELinux but the panic is happening
>> in a SELinux hook.
>
> I just mean that, being Ubuntu,  the system (userland) isn't configured to
> use selinux.  SELinux is just enabled in the kernel config.

Thanks for the quick response, I'll setup an Ubuntu guest and see if I
can reproduce this ... something is odd.  Anything non-standard about
your guest install or anything else you think might be helpful?

-- 
paul moore
www.paul-moore.com
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