Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932117Ab2HGWQV (ORCPT ); Tue, 7 Aug 2012 18:16:21 -0400 Received: from 50-56-35-84.static.cloud-ips.com ([50.56.35.84]:41452 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756481Ab2HGWQS (ORCPT ); Tue, 7 Aug 2012 18:16:18 -0400 Date: Tue, 7 Aug 2012 22:17:32 +0000 From: "Serge E. Hallyn" To: Paul Moore Cc: John Stultz , lkml , "Serge E. Hallyn" , James Morris , selinux@tycho.nsa.gov Subject: Re: NULL pointer dereference in selinux_ip_postroute_compat Message-ID: <20120807221731.GA25441@mail.hallyn.com> References: <50215A7E.8000701@linaro.org> <50218F7E.1060004@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2454 Lines: 62 Quoting Paul Moore (paul@paul-moore.com): > On Tue, Aug 7, 2012 at 5:58 PM, John Stultz wrote: > > On 08/07/2012 02:50 PM, Paul Moore wrote: > >> > >> On Tue, Aug 7, 2012 at 2:12 PM, John Stultz > >> 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? The problem seems to be that selinux_nf_ip_init() was called, which registers the selinux_ipv4_ops (and ipv6). Those should not get registered if selinux ends up not being loaded (as in, if apparmor is loaded first), since as you've found here the selinux lsm hooks won't be called to set call selinux_sk_alloc_security(). I assume what's happening is that CONFIG_SECURITY_SELINUX_BOOTPARAM_VALUE was set to 1, but selinux ended up being set to disabled after the __initcall(selinux_nf_ip_init) ran? Weird. -serge -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/