From: Bart Van Assche <bvanassche@acm.org>
To: Michael Christie <michaelc@cs.wisc.edu>
Cc: linux-scsi <linux-scsi@vger.kernel.org>,
James Bottomley <jbottomley@parallels.com>,
Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>,
Chanho Min <chanho.min@lge.com>
Subject: Re: [PATCH] Fix a use-after-free triggered by device removal
Date: Thu, 06 Sep 2012 19:58:54 +0200 [thread overview]
Message-ID: <5048E45E.1070302@acm.org> (raw)
In-Reply-To: <91D94272-CA62-4E68-87D7-CE77DE776CC9@cs.wisc.edu>
_suOn 09/06/12 18:27, Michael Christie wrote:
> On Sep 3, 2012, at 9:12 AM, Bart Van Assche <bvanassche@acm.org> wrote:
>> If the put_device() call in scsi_request_fn() drops the sdev refcount
>> to zero then the spin_lock() call after the put_device() call triggers
>> a use-after-free. Avoid that by making sure that blk_cleanup_queue()
>> can only finish after all active scsi_request_fn() calls have returned.
>
> If we have this patch http://marc.info/?l=linux-scsi&m=134453905402413&w=2
> it seems we have all the scsi layer callers of the request_fn/
> *blk_run_queue holding a reference to the device when they make the call.
> Right, or are there some other places missing?
>
> What are the other places we can call the request_fn without already
> holding a reference to the device? Is it the block layer? Is that why we
> need this patch?
Hello Mike,
The purpose of this patch is indeed to make *blk_run_queue() calls from
the block layer safe. There are several direct or indirect
*blk_run_queue() calls in the block layer where a reference on the queue
is held but not on the sdev, e.g. in the md, dm and bsg drivers.
Bart.
next prev parent reply other threads:[~2012-09-06 17:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-03 14:12 [PATCH] Fix a use-after-free triggered by device removal Bart Van Assche
2012-09-06 16:27 ` Michael Christie
2012-09-06 17:58 ` Bart Van Assche [this message]
2012-09-06 18:14 ` Mike Christie
2012-09-06 18:52 ` Bart Van Assche
2012-09-06 23:20 ` Tejun Heo
2012-09-07 6:57 ` Bart Van Assche
2012-09-10 23:38 ` Tejun Heo
2012-09-11 6:42 ` Bart Van Assche
2012-09-12 20:53 ` Tejun Heo
2012-09-13 7:26 ` Bart Van Assche
2012-09-13 16:53 ` Tejun Heo
2012-09-13 18:27 ` Bart Van Assche
2012-09-13 19:25 ` Tejun Heo
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