From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>,
linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org,
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 10:17:04 -0600 [thread overview]
Message-ID: <77cbc472-279e-5c9a-3428-b1a485b3f1b7@kernel.dk> (raw)
In-Reply-To: <20210425085753.2617424-1-ming.lei@redhat.com>
On 4/25/21 2:57 AM, 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
>
> This patchset fixes the request UAF issue by one simpler approach,
> without any change in fast path.
>
> 1) always complete request synchronously when the completing is run
> via blk_mq_tagset_busy_iter(), done in 1st two patches
>
> 2) grab request's ref before calling ->fn in blk_mq_tagset_busy_iter,
> and release it after calling ->fn, so ->fn won't be called for one
> request if its queue is frozen, done in 3rd patch
>
> 3) clearing any stale request referred in ->rqs[] before freeing the
> request pool, one per-tags spinlock is added for protecting
> grabbing request ref vs. clearing ->rqs[tag], so UAF by refcount_inc_not_zero
> in bt_tags_iter() is avoided, done in 4th patch.
I'm going to pull the UAF series for now so we don't need to do a series
of reverts if we deem this a better approach. I'll take a further look
at it tomorrow.
--
Jens Axboe
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next prev parent reply other threads:[~2021-04-25 16:17 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 ` [PATCH 0/8] blk-mq: fix request UAF related with iterating over tagset requests Ming Lei
2021-04-25 20:53 ` 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 [this message]
2021-04-25 18:39 ` Bart Van Assche
2021-04-25 20:18 ` Jens Axboe
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