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From: Tejun Heo <tj@kernel.org>
To: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Vivek Goyal <vgoyal@redhat.com>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH] blkcg: Fix use-after-free of q->root_blkg and q->root_rl.blkg
Date: Thu, 18 Oct 2012 14:21:33 -0700	[thread overview]
Message-ID: <20121018212133.GL13370@google.com> (raw)
In-Reply-To: <507E7030.9070607@ce.jp.nec.com>

On Wed, Oct 17, 2012 at 05:45:36PM +0900, Jun'ichi Nomura wrote:
> blk_put_rl() does not call blkg_put() for q->root_rl because we
> don't take request list reference on q->root_blkg.
> However, if root_blkg is once attached then detached (freed),
> blk_put_rl() is confused by the bogus pointer in q->root_blkg.
> 
> For example, with !CONFIG_BLK_DEV_THROTTLING &&
> CONFIG_CFQ_GROUP_IOSCHED,
> switching IO scheduler from cfq to deadline will cause system stall
> after the following warning with 3.6:
...
> This patch clears q->root_blkg and q->root_rl.blkg when root blkg
> is destroyed.
> 
> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
> Acked-by: Vivek Goyal <vgoyal@redhat.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Jens Axboe <axboe@kernel.dk>

Acked-by: Tejun Heo <tj@kernel.org>

Jens, this one needs Cc: stable.

Thanks.

-- 
tejun

  reply	other threads:[~2012-10-18 21:21 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-10  5:11 [PATCH] Fix use-after-free of q->root_blkg and q->root_rl.blkg Jun'ichi Nomura
2012-10-10 15:59 ` Vivek Goyal
2012-10-11  1:31   ` Jun'ichi Nomura
2012-10-11 18:55     ` Vivek Goyal
2012-10-16 23:20     ` Tejun Heo
2012-10-17  0:02       ` Jun'ichi Nomura
2012-10-17  8:45         ` [PATCH] blkcg: " Jun'ichi Nomura
2012-10-18 21:21           ` Tejun Heo [this message]
2012-10-22 18:43           ` Jens Axboe
2012-10-17 13:47         ` [PATCH] " Vivek Goyal
2012-10-18  2:56           ` Jun'ichi Nomura
2012-10-18 13:31             ` Vivek Goyal
2012-10-18 21:20               ` Tejun Heo
2012-10-19 14:53                 ` Vivek Goyal
2012-10-22  0:55                   ` Jun'ichi Nomura
2012-10-22  1:15                 ` [PATCH] blkcg: stop iteration early if root_rl is the only request list Jun'ichi Nomura
2012-10-22 15:31                   ` Vivek Goyal
2012-10-22 18:43                   ` Jens Axboe

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