From: Dave Chinner <david@fromorbit.com>
To: Lachlan McIlroy <lachlan@sgi.com>
Cc: xfs-dev <xfs-dev@sgi.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] Fix use-after-free with log and quotas
Date: Tue, 16 Sep 2008 14:08:25 +1000 [thread overview]
Message-ID: <20080916040825.GO5811@disturbed> (raw)
In-Reply-To: <48CDCB04.1040402@sgi.com>
On Mon, Sep 15, 2008 at 12:40:04PM +1000, Lachlan McIlroy wrote:
> Dave Chinner wrote:
>> On Fri, Sep 12, 2008 at 06:41:07PM +1000, Lachlan McIlroy wrote:
>>> Destroying the quota stuff on unmount can access the log - ie XFS_QM_DONE()
>>> ends up in xfs_dqunlock() which calls xfs_trans_unlocked_item() and then
>>> xfs_log_move_tail(). By this time the log has already been destroyed.
>>> Just move the cleanup of the quota code earlier in xfs_unmountfs() before
>>> the call to xfs_log_unmount(). Moving XFS_QM_DONE() up near
>>> XFS_QM_DQPURGEALL() seems like a good spot.
>>
>> FWIW, has this been actually seen in the real world?
> Yes. And easy to reproduce too.
Care to provide details about the test case, then? I can't help if
you keep me in the dark....
>> torn down the AIL and there should be no log items in the system
>> that are in the AIL....
> That should be the case but clearly not happening. Pete is investigating
> an issue right now where a dquot is not getting removed from the AIL when
> it should. Until we've got to the bottom of that problem I'd prefer to at
> least avoid this use after free issue.
No point in putting a bandaid in if you're already in the process of
trying to find the real cause....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2008-09-16 4:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-12 8:41 [PATCH] Fix use-after-free with log and quotas Lachlan McIlroy
2008-09-12 8:43 ` Christoph Hellwig
2008-09-13 4:02 ` Dave Chinner
2008-09-15 2:40 ` Lachlan McIlroy
2008-09-16 4:08 ` Dave Chinner [this message]
2008-09-16 6:36 ` Lachlan McIlroy
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