lkml.org 
[lkml]   [2011]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: 3.0.0-rc2-git1 -- BUG: sleeping function called from invalid context at mm/slub.c:847
On 06/08/2011 01:09 PM, David Rientjes wrote:
> On Wed, 8 Jun 2011, Miles Lane wrote:
>
>> BUG: sleeping function called from invalid context at mm/slub.c:847
>> in_atomic(): 1, irqs_disabled(): 0, pid: 1583, name: cupsd
>> 2 locks held by cupsd/1583:
>> #0: (tasklist_lock){.+.+.+}, at: [<ffffffff8104dafa>] do_prlimit+0x61/0x189
>> #1: (&(&p->alloc_lock)->rlock){+.+.+.}, at: [<ffffffff8104db2d>]
>> do_prlimit+0x94/0x189
>> Pid: 1583, comm: cupsd Not tainted 3.0.0-rc2-git1 #7
>> Call Trace:
>> [<ffffffff8102ebf2>] __might_sleep+0x10d/0x112
>> [<ffffffff810e6f46>] slab_pre_alloc_hook.isra.49+0x2d/0x33
>> [<ffffffff810e7bc4>] kmem_cache_alloc+0x22/0x132
>> [<ffffffff8105b6e6>] prepare_creds+0x35/0xe4
>> [<ffffffff811c0675>] aa_replace_current_profile+0x35/0xb2
>> [<ffffffff811c4d2d>] aa_current_profile+0x45/0x4c
>> [<ffffffff811c4d4d>] apparmor_task_setrlimit+0x19/0x3a
>> [<ffffffff811beaa5>] security_task_setrlimit+0x11/0x13
>> [<ffffffff8104db6b>] do_prlimit+0xd2/0x189
>> [<ffffffff8104dea9>] sys_setrlimit+0x3b/0x48
>> [<ffffffff814062bb>] system_call_fastpath+0x16/0x1b
>>
>
> Not sure why this ever actually worked with apparmor if prepare_creds()
> does an unconditional GFP_KERNEL allocation since this codepath hasn't
> changed in at least a year and we're holding a spinlock from setrlimit.
> John?

Hrmm, I am assuming it was missed because the profile replacement that
causes the prepare_creds() to be called is a rare condition when apparmor
is in use. It will only occur when policy has been replaced and only if
the task doing the task_setrlimit() hasn't already updated its cred else
where. It is clearly wrong, patch included below.

---
From 99710968923ddc1f89029d98b2eb7d45b11323dc Mon Sep 17 00:00:00 2001
From: John Johansen <john.johansen@canonical.com>
Date: Wed, 8 Jun 2011 15:03:58 -0700
Subject: [PATCH] AppArmor: Fix sleep in invalid context from task_setrlimit

Affected kernels 2.6.36 - 3.0

AppArmor may do a GFP_KERNEL memory allocation with task_lock(tsk->group_leader);
held when called from security_task_setrlimit. This will only occur when the
task's current policy has been replaced, and the task's creds have not been
updated before entering the LSM security_task_setrlimit() hook.

As reported by Miles Lane

BUG: sleeping function called from invalid context at mm/slub.c:847
in_atomic(): 1, irqs_disabled(): 0, pid: 1583, name: cupsd
2 locks held by cupsd/1583:
#0: (tasklist_lock){.+.+.+}, at: [<ffffffff8104dafa>] do_prlimit+0x61/0x189
#1: (&(&p->alloc_lock)->rlock){+.+.+.}, at: [<ffffffff8104db2d>]
do_prlimit+0x94/0x189
Pid: 1583, comm: cupsd Not tainted 3.0.0-rc2-git1 #7
Call Trace:
[<ffffffff8102ebf2>] __might_sleep+0x10d/0x112
[<ffffffff810e6f46>] slab_pre_alloc_hook.isra.49+0x2d/0x33
[<ffffffff810e7bc4>] kmem_cache_alloc+0x22/0x132
[<ffffffff8105b6e6>] prepare_creds+0x35/0xe4
[<ffffffff811c0675>] aa_replace_current_profile+0x35/0xb2
[<ffffffff811c4d2d>] aa_current_profile+0x45/0x4c
[<ffffffff811c4d4d>] apparmor_task_setrlimit+0x19/0x3a
[<ffffffff811beaa5>] security_task_setrlimit+0x11/0x13
[<ffffffff8104db6b>] do_prlimit+0xd2/0x189
[<ffffffff8104dea9>] sys_setrlimit+0x3b/0x48
[<ffffffff814062bb>] system_call_fastpath+0x16/0x1b
Signed-off-by: John Johansen <john.johansen@canonical.com>
---
security/apparmor/lsm.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index ec1bcec..3d2fd14 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -612,7 +612,7 @@ static int apparmor_setprocattr(struct task_struct *task, char *name,
static int apparmor_task_setrlimit(struct task_struct *task,
unsigned int resource, struct rlimit *new_rlim)
{
- struct aa_profile *profile = aa_current_profile();
+ struct aa_profile *profile = __aa_current_profile();
int error = 0;

if (!unconfined(profile))
--
1.7.4.1


\
 
 \ /
  Last update: 2011-06-09 00:11    [from the cache]
©2003-2011 Jasper Spaans