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From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
	linux-block@vger.kernel.org, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH V3 2/3] blk-mq: avoid to touch q->elevator without any protection
Date: Thu, 16 Jun 2022 08:15:00 +0200	[thread overview]
Message-ID: <20220616061500.GA5144@lst.de> (raw)
In-Reply-To: <20220616014401.817001-3-ming.lei@redhat.com>

On Thu, Jun 16, 2022 at 09:44:00AM +0800, Ming Lei wrote:
> q->elevator is referred in blk_mq_has_sqsched() without any protection,
> no .q_usage_counter is held, no queue srcu and rcu read lock is held,
> so potential use-after-free may be triggered.
> 
> Fix the issue by adding one queue flag for checking if the elevator
> uses single queue style dispatch. Meantime the elevator feature flag
> of ELEVATOR_F_MQ_AWARE isn't needed any more.

I think clearing in common code would be safer, but this does work
as-is, so:

Reviewed-by: Christoph Hellwig <hch@lst.de>

  reply	other threads:[~2022-06-16  6:15 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-16  1:43 [PATCH V3 0/3] blk-mq: three misc patches Ming Lei
2022-06-16  1:43 ` [PATCH V3 1/3] blk-mq: protect q->elevator by ->sysfs_lock in blk_mq_elv_switch_none Ming Lei
2022-06-16  1:44 ` [PATCH V3 2/3] blk-mq: avoid to touch q->elevator without any protection Ming Lei
2022-06-16  6:15   ` Christoph Hellwig [this message]
2022-06-16  1:44 ` [PATCH V3 3/3] blk-mq: don't clear flush_rq from tags->rqs[] Ming Lei
2022-06-16 20:46 ` [PATCH V3 0/3] blk-mq: three misc patches Jens Axboe

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