linux-kernel - Re: [slab corruption] BUG key

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Date:	Thu, 15 Jan 2009 22:17:33 +0100
From:	"Vegard Nossum" <vegard.nossum@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"Pekka Enberg" <penberg@...helsinki.fi>,
	"David Howells" <dhowells@...hat.com>,
	"Michael LeMay" <mdlemay@...ch.ncsc.mil>,
	"James Morris" <jmorris@...ei.org>,
	"Stephen Smalley" <sds@...ho.nsa.gov>,
	"Paul Moore" <paul.moore@...com>, "Eric Paris" <eparis@...hat.com>
Subject: Re: [slab corruption] BUG key_jar: Poison overwritten

On Thu, Jan 15, 2009 at 10:01 PM, Ingo Molnar <mingo@...e.hu> wrote:
>
> * Vegard Nossum <vegard.nossum@...il.com> wrote:
>
>> On Thu, Jan 15, 2009 at 7:16 PM, Ingo Molnar <mingo@...e.hu> wrote:
>> >
>> > -tip testing found the rather scary looking slab corruption:
>> >
>> > [   35.419875] CPU0 attaching sched-domain:
>> > [   35.420101]  domain 0: span 0-1 level CPU
>> > [   35.425883]   groups: 0 1
>> > [   35.428527] CPU1 attaching sched-domain:
>> > [   35.432010]  domain 0: span 0-1 level CPU
>> > [   35.437729]   groups: 1 0
>> > [   37.380005] eth0: no IPv6 routers present
>> > [   44.478286] =============================================================================
>> > [   44.482064] BUG key_jar: Poison overwritten
>> > [   44.482064] -----------------------------------------------------------------------------
>> > [   44.482064]
>> > [   44.482064] INFO: 0xf5f320c0-0xf5f320c0. First byte 0x6a instead of 0x6b
>> > [   44.482064] INFO: Allocated in key_alloc+0xe7/0x30e age=291 cpu=1 pid=2815
>> > [   44.482064] INFO: Freed in key_cleanup+0xd8/0xdd age=292 cpu=1 pid=2520
>> > [   44.482064] INFO: Slab 0xc1f9cfb8 objects=21 used=2 fp=0xf5f320c0 flags=0x400000c3
>> > [   44.482064] INFO: Object 0xf5f320c0 @offset=192 fp=0xf5f32240
>> > [   44.482064]
>> > [   44.482064] Bytes b4 0xf5f320b0:  7c 05 ff ff 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a |.��ZZZZZZZZZZZZ
>> > [   44.482064]   Object 0xf5f320c0:  6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b jkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f320d0:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f320e0:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f320f0:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f32100:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f32110:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f32120:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f32130:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
>> > [   44.482064]   Object 0xf5f32140:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5             kkkkkkkkkkk�
>> > [   44.482064]  Redzone 0xf5f3214c:  bb bb bb bb                                     ����
>> > [   44.482064]  Padding 0xf5f32174:  5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a             ZZZZZZZZZZZZ
>> > [   44.482064] Pid: 2832, comm: sudo Not tainted 2.6.29-rc1-tip-01097-gf5d0b1b-dirty #16445
>> > [   44.482064] Call Trace:
>> > [   44.482064]  [<c018e25c>] print_trailer+0xcd/0xd5
>> > [   44.482064]  [<c018e2dc>] check_bytes_and_report+0x78/0x94
>> > [   44.482064]  [<c018e55c>] check_object+0xa9/0x191
>> > [   44.482064]  [<c018eff3>] __slab_alloc+0x365/0x42c
>> > [   44.482064]  [<c0144dda>] ? trace_hardirqs_off+0xb/0xd
>> > [   44.482064]  [<c018f369>] kmem_cache_alloc+0x64/0xc1
>> > [   44.482064]  [<c02d040e>] ? key_alloc+0xe7/0x30e
>> > [   44.482064]  [<c02d040e>] ? key_alloc+0xe7/0x30e
>> > [   44.482064]  [<c02d040e>] key_alloc+0xe7/0x30e
>> > [   44.482064]  [<c02d1429>] keyring_alloc+0x24/0x58
>> > [   44.482064]  [<c02d2781>] install_session_keyring_to_cred+0x43/0x92
>> > [   44.482064]  [<c02d2d61>] lookup_user_key+0xe0/0x30b
>> > [   44.482064]  [<c02d17ab>] keyctl_get_keyring_ID+0x12/0x2e
>> > [   44.482064]  [<c02d22c2>] sys_keyctl+0x36/0xe3
>> > [   44.482064]  [<c0102d55>] sysenter_do_call+0x12/0x35
>> > [   44.482064] FIX key_jar: Restoring 0xf5f320c0-0xf5f320c0=0x6b
>> > [   44.482064]
>> > [   44.482064] FIX key_jar: Marking all objects used
>> >
>> > Config attached. The system seemed to stay intact after this incident.
>>
>>
>> Are you sure this is the right config?
>>
>> # Security options
>> #
>> # CONFIG_KEYS is not set
>>
>> ...sys_keyctl() returns -ENOSYS...!?
>
> no, sorry. The right 'bad' config attached.

Are you sure, is this expected?

  CC      kernel/printk.o
cc1: warnings being treated as errors
arch/x86/kernel/cpu/intel_cacheinfo.c: In function 'show_cache_disable':
arch/x86/kernel/cpu/intel_cacheinfo.c:710: error: unused variable 'mask'
arch/x86/kernel/cpu/intel_cacheinfo.c: In function 'store_cache_disable':
arch/x86/kernel/cpu/intel_cacheinfo.c:745: error: unused variable 'mask'
make[2]: *** [arch/x86/kernel/cpu/intel_cacheinfo.o] Error 1
make[1]: *** [arch/x86/kernel/cpu] Error 2
make: *** [arch/x86/kernel] Error 2
make: *** Waiting for unfinished jobs....

Will restart make with CONFIG_ALLOW_WARNINGS=y...


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036