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From: Tejun Heo <tj@kernel.org>
To: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Rabin Vincent <rabin@rab.in>, Jens Axboe <axboe@fb.com>,
	Jan Kara <jack@suse.cz>, Al Viro <viro@zeniv.linux.org.uk>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] bdev: fix NULL pointer dereference in sync()/close() race
Date: Mon, 29 Aug 2016 15:55:40 -0400	[thread overview]
Message-ID: <20160829195540.GE28713@mtj.duckdns.org> (raw)
In-Reply-To: <a4a122ba-ed36-f890-56c3-96d1660378a4@oracle.com>

Hello,

On Sat, Aug 27, 2016 at 11:30:22AM +0200, Vegard Nossum wrote:
> > Don't know what's the right fix, but I posted a slightly different one
> > for the same crash some months ago:
> > https://patchwork.kernel.org/patch/8556941/
> > 
> 
> Ah, I'm sorry, I didn't see that.
> 
> Your patch is 100% identical to my first attempt at a fix and I can
> confirm that it also fixes the problem for me.
> 
> If people who are more savvy in block/fs code could ack the locking bits
> I think we should apply the patch ASAP because it's an easy local DOS if
> you have (open/read) access to any block device.

I think the right thing to do there is doing blkdev_get() /
blkdev_put() around func() invocation in iterate_bdevs() rather than
holding bd_mutex across the callback.  Can you please verify whether
that works?

Thanks.

-- 
tejun

  reply	other threads:[~2016-08-29 19:55 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-27  7:07 [PATCH] bdev: fix NULL pointer dereference in sync()/close() race Vegard Nossum
2016-08-27  9:03 ` Rabin Vincent
2016-08-27  9:30   ` Vegard Nossum
2016-08-29 19:55     ` Tejun Heo [this message]
2016-08-29 20:49       ` Vegard Nossum
2016-08-29 20:54         ` Tejun Heo
2016-08-29 21:33       ` Vegard Nossum
2016-08-29 23:49         ` Tejun Heo

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