Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932980Ab2HHTPd (ORCPT ); Wed, 8 Aug 2012 15:15:33 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:45783 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757643Ab2HHTPa (ORCPT ); Wed, 8 Aug 2012 15:15:30 -0400 Message-ID: <5022BAA2.90606@us.ibm.com> Date: Wed, 08 Aug 2012 12:14:42 -0700 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120714 Thunderbird/14.0 MIME-Version: 1.0 To: "Serge E. Hallyn" CC: Paul Moore , lkml , James Morris , selinux@tycho.nsa.gov, Eric Dumazet , john.johansen@canonical.com Subject: Re: NULL pointer dereference in selinux_ip_postroute_compat References: <50215A7E.8000701@linaro.org> <50218F7E.1060004@linaro.org> <20120807221731.GA25441@mail.hallyn.com> <502198B4.8040503@linaro.org> In-Reply-To: <502198B4.8040503@linaro.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12080819-6148-0000-0000-00000871C486 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2781 Lines: 78 On 08/07/2012 03:37 PM, John Stultz wrote: > On 08/07/2012 03:17 PM, Serge E. Hallyn wrote: >> 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. [snip] >> 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(). > This sounds about right: > root@testvm:~# dmesg | grep SELinux > [ 0.004578] SELinux: Initializing. > [ 0.005704] SELinux: Starting in permissive mode > [ 2.235034] SELinux: Registering netfilter hooks > >> 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. > This looks right as well: > > # zcat config.gz | grep SELINUX > CONFIG_SECURITY_SELINUX=y > CONFIG_SECURITY_SELINUX_BOOTPARAM=y > CONFIG_SECURITY_SELINUX_BOOTPARAM_VALUE=1 > CONFIG_SECURITY_SELINUX_DISABLE=y > CONFIG_SECURITY_SELINUX_DEVELOP=y > CONFIG_SECURITY_SELINUX_AVC_STATS=y > CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE=1 > # CONFIG_SECURITY_SELINUX_POLICYDB_VERSION_MAX is not set > CONFIG_DEFAULT_SECURITY_SELINUX=y > > > Since the problem isn't completely obvious, I'm starting a bisection > to narrow this down some more. So I bisected this down and it seems to be the following commit: commit be9f4a44e7d41cee50ddb5f038fc2391cbbb4046 Author: Eric Dumazet Date: Thu Jul 19 07:34:03 2012 +0000 ipv4: tcp: remove per net tcp_sock It doesn't revert totally cleanly, but after fixing up the rejections and booting with this patch removed on top of Linus' head the oops on shutdown goes away. thanks -john -- 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/