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From: Ming Lei <ming.lei@redhat.com>
To: linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>,
	Khazhy Kumykov <khazhy@google.com>,
	Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
	Hannes Reinecke <hare@suse.de>,
	John Garry <john.garry@huawei.com>,
	David Jeffery <djeffery@redhat.com>
Subject: Re: [PATCH 0/8] blk-mq: fix request UAF related with iterating over tagset requests
Date: Sun, 25 Apr 2021 17:27:34 +0800	[thread overview]
Message-ID: <YIU2BhuYZAAgonN0@T590> (raw)
In-Reply-To: <20210425085753.2617424-1-ming.lei@redhat.com>

On Sun, Apr 25, 2021 at 04:57:45PM +0800, Ming Lei wrote:
> Hi Guys,
> 
> Revert 4 patches from Bart which try to fix request UAF issue related
> with iterating over tagset wide requests, because:
> 
> 1) request UAF caused by normal completion vs. async completion during
> iterating can't be covered[1]
> 
> 2) clearing ->rqs[] is added in fast path, which causes performance loss
> by 1% according to Bart's test
> 
> 3) Bart's approach is too complicated, and some changes aren't needed,
> such as adding two versions of tagset iteration

4) synchronize_rcu() is added before shutting down one request queue,
which may slow down reboot/poweroff very much on big systems with lots of
HBAs in which lots of LUNs are attached.

5) freeing request pool in updating nr_requests isn't covered.

Thanks,
Ming


  parent reply	other threads:[~2021-04-25  9:27 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-25  8:57 [PATCH 0/8] blk-mq: fix request UAF related with iterating over tagset requests Ming Lei
2021-04-25  8:57 ` [PATCH 1/8] Revert "blk-mq: Fix races between blk_mq_update_nr_hw_queues() and iterating over tags" Ming Lei
2021-04-25  8:57 ` [PATCH 2/8] Revert "blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list" Ming Lei
2021-04-25  8:57 ` [PATCH 3/8] Revert "blk-mq: Fix races between iterating over requests and freeing requests" Ming Lei
2021-04-25  8:57 ` [PATCH 4/8] Revert "blk-mq: Introduce atomic variants of blk_mq_(all_tag|tagset_busy)_iter" Ming Lei
2021-04-25  8:57 ` [PATCH 5/8] blk-mq: blk_mq_complete_request_locally Ming Lei
2021-04-25  8:57 ` [PATCH 6/8] block: drivers: complete request locally from blk_mq_tagset_busy_iter Ming Lei
2021-04-26  3:02   ` Bart Van Assche
2021-04-26  6:24     ` Ming Lei
2021-04-27  8:54       ` Ming Lei
2021-04-25  8:57 ` [PATCH 7/8] blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter Ming Lei
2021-04-25 18:55   ` Bart Van Assche
2021-04-26  0:41     ` Ming Lei
2021-04-25  8:57 ` [PATCH 8/8] blk-mq: clear stale request in tags->rq[] before freeing one request pool Ming Lei
2021-04-25 20:42   ` Bart Van Assche
2021-04-26  0:49     ` Ming Lei
2021-04-26  1:50       ` Bart Van Assche
2021-04-26  2:07         ` Ming Lei
2021-04-25  9:27 ` Ming Lei [this message]
2021-04-25 20:53   ` [PATCH 0/8] blk-mq: fix request UAF related with iterating over tagset requests Bart Van Assche
2021-04-26  1:19     ` Ming Lei
2021-04-26  1:57       ` Bart Van Assche
2021-04-25 16:17 ` Jens Axboe
2021-04-25 18:39   ` Bart Van Assche
2021-04-25 20:18     ` Jens Axboe

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