Messages in this thread | | | Date | Wed, 08 Aug 2012 12:14:42 -0700 | From | John Stultz <> | Subject | Re: NULL pointer dereference in selinux_ip_postroute_compat |
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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 <john.stultz@linaro.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@linaro.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. [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 <edumazet@google.com> 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
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