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Re: Kernel oops+crash on repeated auditd restarts



Here's a trace with debugging turned way up plus a few extra printk's
added to fs/notify/mark.c. I'm looping through private_destroy_list
before and after the call to synchronize_srcu.

I can reproduce this reliably with kvm with 2 virtual processors:
Linux desktop 3.4.0-rc3-oops1+ #1 SMP Tue Apr 17 09:59:44 PDT 2012
x86_64 GNU/Linux

Cheers,
peter

On Thu, Apr 5, 2012 at 2:07 PM, Eric Paris <eparis redhat com> wrote:
> please please please keep on list.  Everything you say might help track
> it down!
>
> On Thu, 2012-04-05 at 14:03 -0700, Peter Moody wrote:
>> (please let me know if I should take this off-list)
>>
>> One other thing (again, maybe already known), but this seems to be
>> exacerbated by SMP. On my machine, I can't reproduce the crash if I
>> booth with maxcpus=1.
>>
>> Still hunting.
>>
>> Cheers,
>> peter
>>
>> On Tue, Apr 3, 2012 at 9:15 AM, Peter Moody <pmoody google com> wrote:
>> > This may already be known, but the issue seems to be limited to watch
>> > rules. With any watch rules, I can reliably crash my machine while
>> > freeing a watch rule after only starting/stopping auditd a few times.
>> > With no watch rules, I have no issues.
>> >
>> > Cheers,
>> > peter
>> >
>> > On Wed, Mar 28, 2012 at 11:44 PM, Valentin Avram <aval13 gmail com> wrote:
>> >> Yes, i know that patch. It made it into kernel 3.2.2. I tested it
>> >> successfully (oops in 3.2.1, no oops in 3.2.9), but this oops i'm seeing is
>> >> also in 3.2.9.
>> >>
>> >> I monitored changelogs since 3.2.1 to 3.2.12 but there were no fixes either
>> >> in audit subsystem or in fsnotify. I'll try to reproduce in latest 3.2.13
>> >> and repost the oops, but i'm 99% confident it will be the same.
>> >>
>> >> Sadly nobody except you seems to pay attention to this problem, probably
>> >> because it requires special conditions to reproduce (really, who starts and
>> >> stops auditd every 5 seconds on a production server?). We only ran into it
>> >> because one of our servers would randomly oops and then freeze about each
>> >> month after stopping and then starting
>> >>
>> >> auditd
>> >>
>> >> every morning (and the stop-start sequence was needed to workaround a bug
>> >> somewhere that would hang a
>> >>
>> >> gzip
>> >>
>> >> running on a file outside a watched folder).
>> >>
>> >> Anyway, as a last note, i have a feeling that the oops is not exactly
>> >> random, there is a pattern, just that i haven't figured it out completely
>> >> yet.
>> >>
>> >> Will keep you
>> >>
>> >> uptodate
>> >>
>> >> with the things i find out.
>> >>
>> >> V.
>> >>
>> >> On Mar 29, 2012 4:14 AM, "Eric Paris" <eparis redhat com> wrote:
>> >>>
>> >>> That patch fixes a BUG() .  The report has a NULL ptr deref and some
>> >>> apparent list correuption....  Sadly they aren't the same....
>> >>>
>> >>> On Wed, 2012-03-28 at 15:42 -0700, Peter Moody wrote:
>> >>> > fyi: this patch [1] seems to fix the issue for me. The explanation in
>> >>> > the subject would reliably oops my machine.
>> >>> >
>> >>> > [1]
>> >>> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=fed474857efbed79cd390d0aee224231ca718f63
>> >>> >
>> >>> > On Wed, Mar 28, 2012 at 1:51 PM, Peter Moody <pmoody google com> wrote:
>> >>> > > Are you still able to reliably reproduce this oops? I'm trying to
>> >>> > > track this down because this bug (or a very similar bug) is causing
>> >>> > > some significant headaches here at work, but I haven't had a lot of
>> >>> > > luck. I'm using usermode linux, though, so that might be interfering
>> >>> > > with things.
>> >>> > >
>> >>> > > On Mon, Mar 5, 2012 at 12:35 AM, Valentin Avram <aval13 gmail com>
>> >>> > > wrote:
>> >>> > >> Finally i found some time and spare server to retest the oops and
>> >>> > >> list_add
>> >>> > >> corruptions i was getting with the 3.x kernels and auditd 2.1.3.
>> >>> > >>
>> >>> > >> I tested now with gentoo's latest stable 3.2.1-gentoo-r2 and
>> >>> > >> kernel.org's
>> >>> > >> 3.2.9.
>> >>> > >>
>> >>> > >> Both get the oops/BUG in the same way and after that, they keep
>> >>> > >> pouring
>> >>> > >> list_add corruptions with audit_prune_tre(truncated?) and auditctl as
>> >>> > >> comms.
>> >>> > >>
>> >>> > >> Since this is not about Gentoo's kernel only, i'll post here the oops
>> >>> > >> in
>> >>> > >> 3.2.9 and also attach some list_add corruptions.
>> >>> > >>
>> >>> > >> 3.2.9 BUG:
>> >>> > >>
>> >>> > >> kernel: [  301.240011] BUG: unable to handle kernel NULL pointer
>> >>> > >> dereference
>> >>> > >> at   (null)
>> >>> > >> kernel: [  301.240305] IP: [<c1238dd0>] __list_del_entry+0x20/0xe0
>> >>> > >> kernel: [  301.240481] *pdpt = 0000000000000000 *pde =
>> >>> > >> f000ddc8f000ddc8
>> >>> > >> kernel: [  301.240698] Oops: 0000 [#1] SMP
>> >>> > >> kernel: [  301.240910]
>> >>> > >> kernel: [  301.241030] Pid: 642, comm: fsnotify_mark Not tainted
>> >>> > >> 3.2.9-drbd-version3 #1 Dell Inc. PowerEdge 2950/0CX396
>> >>> > >> kernel: [  301.241370] EIP: 0060:[<c1238dd0>] EFLAGS: 00010287 CPU: 6
>> >>> > >> kernel: [  301.241498] EIP is at __list_del_entry+0x20/0xe0
>> >>> > >> kernel: [  301.241623] EAX: f4fae544 EBX: f47cffa4 ECX: ffffffff EDX:
>> >>> > >> 00000000
>> >>> > >> kernel: [  301.241751] ESI: f4fae544 EDI: f4fae508 EBP: f47cff7c ESP:
>> >>> > >> f47cff64
>> >>> > >> kernel: [  301.241879]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
>> >>> > >> kernel: [  301.242005] Process fsnotify_mark (pid: 642, ti=f47ce000
>> >>> > >> task=f4f47c00 task.ti=f47ce000)
>> >>> > >> kernel: [  301.242207] Stack:
>> >>> > >> kernel: [  301.242327]  c10813c0 f47cffa4 f4f47c00 f4e70888 f47cff7c
>> >>> > >> f47cffa4 f47cffb8 c10f6976
>> >>> > >> kernel: [  301.242882]  ffffffc3 f4f47c00 f4f47c00 00000000 f4f47c00
>> >>> > >> c10530c0 f47cff9c f47cff9c
>> >>> > >> kernel: [  301.243438]  f4fae544 f4fae544 f4c47f58 00000000 c10f68f0
>> >>> > >> f47cffe4 c1052834 00000000
>> >>> > >> kernel: [  301.243995] Call Trace:
>> >>> > >> kernel: [  301.244119]  [<c10813c0>] ?
>> >>> > >> rcu_check_callbacks+0x110/0x110
>> >>> > >> kernel: [  301.244248]  [<c10f6976>] fsnotify_mark_destroy+0x86/0x120
>> >>> > >> kernel: [  301.244377]  [<c10530c0>] ? abort_exclusive_wait+0x80/0x80
>> >>> > >> kernel: [  301.244504]  [<c10f68f0>] ? fsnotify_put_mark+0x30/0x30
>> >>> > >> kernel: [  301.244631]  [<c1052834>] kthread+0x74/0x80
>> >>> > >> kernel: [  301.244756]  [<c10527c0>] ?
>> >>> > >> kthread_flush_work_fn+0x10/0x10
>> >>> > >> kernel: [  301.244885]  [<c1582ab6>] kernel_thread_helper+0x6/0xd
>> >>> > >> kernel: [  301.245011] Code: 55 f4 8b 45 f8 e9 75 ff ff ff 90 55 89
>> >>> > >> e5 53 83
>> >>> > >> ec 14 8b 08 8b 50 04 81 f9 00 01 10 00 74 24 81 fa 00 02 20 00 0f 84
>> >>> > >> 8e 00
>> >>> > >> 00 00 <8b> 1a 39 d8 75 62 8b 59 04 39 d8 75 35 89 51 04 89 0a 83 c4
>> >>> > >> 14
>> >>> > >> kernel: [  301.248195] EIP: [<c1238dd0>] __list_del_entry+0x20/0xe0
>> >>> > >> SS:ESP
>> >>> > >> 0068:f47cff64
>> >>> > >> kernel: [  301.248414] CR2: 0000000000000000
>> >>> > >> kernel: [  301.248538] ---[ end trace 15082dbfb353f84c ]---
>> >>> > >>
>> >>> > >> The kernel was compiled with the following DEBUG support (the bolded
>> >>> > >> one
>> >>> > >> were requested by Gentoo's Dev:
>> >>> > >> CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC=y
>> >>> > >> CONFIG_SLUB_DEBUG=y
>> >>> > >> CONFIG_HAVE_DMA_API_DEBUG=y
>> >>> > >> CONFIG_X86_DEBUGCTLMSR=y
>> >>> > >> CONFIG_PNP_DEBUG_MESSAGES=y
>> >>> > >> CONFIG_AIC94XX_DEBUG=y
>> >>> > >> CONFIG_USB_DEBUG=y
>> >>> > >> CONFIG_DEBUG_KERNEL=y
>> >>> > >> CONFIG_SCHED_DEBUG=y
>> >>> > >> CONFIG_DEBUG_RT_MUTEXES=y
>> >>> > >> CONFIG_DEBUG_PI_LIST=y
>> >>> > >> CONFIG_DEBUG_BUGVERBOSE=y
>> >>> > >> CONFIG_DEBUG_INFO=y
>> >>> > >> CONFIG_DEBUG_MEMORY_INIT=y
>> >>> > >> CONFIG_DEBUG_LIST=y
>> >>> > >> CONFIG_DEBUG_STACKOVERFLOW=y
>> >>> > >> CONFIG_DEBUG_RODATA=y
>> >>> > >> CONFIG_DEBUG_RODATA_TEST=y
>> >>> > >>
>> >>> > >> I attached the kernel config i used for 3.2.9 to generate this oops
>> >>> > >> and
>> >>> > >> warnings.
>> >>> > >>
>> >>> > >> From the list_add warnings that come after, out of 805 warnings i
>> >>> > >> processed,
>> >>> > >> after masking with XXXXX the PID and next= values that kept changing
>> >>> > >> in
>> >>> > >> every one, i got 26 types of MD5. I also attached the files relevant
>> >>> > >> as an
>> >>> > >> archive to this email.
>> >>> > >>
>> >>> > >> The Gentoo bug i opened is sleeping, it seems nobody has the time to
>> >>> > >> at
>> >>> > >> least test to confirm or not the problems i'm seeing (or everybody's
>> >>> > >> thinking that nobody would restart auditd so often, so the bug it's
>> >>> > >> not that
>> >>> > >> serious).
>> >>> > >>
>> >>> > >>
>> >>> > >> Thank you for your time.
>> >>> > >>
>> >>> > >> On Wed, Feb 8, 2012 at 6:11 PM, Valentin Avram <aval13 gmail com>
>> >>> > >> wrote:
>> >>> > >>
>> >>> > >>
>> >>> > >> --
>> >>> > >> Linux-audit mailing list
>> >>> > >> Linux-audit redhat com
>> >>> > >> https://www.redhat.com/mailman/listinfo/linux-audit
>> >>> > >
>> >>> > >
>> >>> > >
>> >>> > > --
>> >>> > > Peter Moody      Google    1.650.253.7306
>> >>> > > Security Engineer  pgp:0xC3410038
>> >>> >
>> >>> >
>> >>> >
>> >>>
>> >>>
>> >>
>> >
>> >
>> >
>> > --
>> > Peter Moody      Google    1.650.253.7306
>> > Security Engineer  pgp:0xC3410038
>>
>>
>>
>
>



-- 
Peter Moody      Google    1.650.253.7306
Security Engineer  pgp:0xC3410038

Attachment: trace.gz
Description: GNU Zip compressed data


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