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Re: Kernel oops+crash on repeated auditd restarts



Last thing. moving synchronize_srcu(&fsnotify_mark_srcu) out of the
for(;;) loop in fs/notify/mark.c appears to solve the stability issues
for me. I don't know enough about kernel internals to determine if
this is doing lots of other bad things to my system or not.

Cheers,
peter

On Tue, Apr 17, 2012 at 11:24 AM, Peter Moody <pmoody google com> wrote:
> and my config.gz
>
> On Tue, Apr 17, 2012 at 10:56 AM, Peter Moody <pmoody google com> wrote:
>> 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
>
>
>
> --
> Peter Moody      Google    1.650.253.7306
> Security Engineer  pgp:0xC3410038



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


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