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 V2 2/3] blk-mq: avoid to touch q->elevator without any protection
Date: Wed, 15 Jun 2022 08:50:34 +0200 [thread overview]
Message-ID: <20220615065034.GA23449@lst.de> (raw)
In-Reply-To: <20220615064826.773067-3-ming.lei@redhat.com>
On Wed, Jun 15, 2022 at 02:48:25PM +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.
We still need to clear the flag when switching elevators.
next prev parent reply other threads:[~2022-06-15 6:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-15 6:48 [PATCH V2 0/3] blk-mq: three misc patches Ming Lei
2022-06-15 6:48 ` [PATCH V2 1/3] blk-mq: protect q->elevator by ->sysfs_lock in blk_mq_elv_switch_none Ming Lei
2022-06-15 6:48 ` [PATCH V2 2/3] blk-mq: avoid to touch q->elevator without any protection Ming Lei
2022-06-15 6:50 ` Christoph Hellwig [this message]
2022-06-15 6:56 ` Ming Lei
2022-06-15 6:48 ` [PATCH V2 3/3] blk-mq: don't clear flush_rq from tags->rqs[] Ming Lei
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