From: Bart Van Assche <bvanassche@acm.org>
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.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 V4 2/4] blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter
Date: Thu, 29 Apr 2021 20:06:31 -0700 [thread overview]
Message-ID: <d8ca7a5f-1518-b16b-c65a-d3306991fba4@acm.org> (raw)
In-Reply-To: <20210429023458.3044317-3-ming.lei@redhat.com>
On 4/28/21 7:34 PM, Ming Lei wrote:
> Grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter(), and
> this way will prevent the request from being re-used when ->fn is
> running. The approach is same as what we do during handling timeout.
>
> Fix request UAF related with completion race or queue releasing:
>
> - If one rq is referred before rq->q is frozen, then queue won't be
> frozen before the request is released during iteration.
>
> - If one rq is referred after rq->q is frozen, refcount_inc_not_zero()
> will return false, and we won't iterate over this request.
>
> However, still one request UAF not covered: refcount_inc_not_zero() may
> read one freed request, and it will be handled in next patch.
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
next prev parent reply other threads:[~2021-04-30 3:06 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 2:34 [PATCH V4 0/4] blk-mq: fix request UAF related with iterating over tagset requests Ming Lei
2021-04-29 2:34 ` [PATCH V4 1/4] block: avoid double io accounting for flush request Ming Lei
2021-04-30 2:51 ` Bart Van Assche
2021-04-30 3:12 ` Ming Lei
2021-04-29 2:34 ` [PATCH V4 2/4] blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter Ming Lei
2021-04-30 3:06 ` Bart Van Assche [this message]
2021-04-29 2:34 ` [PATCH V4 3/4] blk-mq: clear stale request in tags->rq[] before freeing one request pool Ming Lei
2021-04-29 14:02 ` David Jeffery
2021-04-29 2:34 ` [PATCH V4 4/4] blk-mq: clearing flush request reference in tags->rqs[] Ming Lei
2021-04-29 14:13 ` David Jeffery
2021-04-30 3:05 ` Bart Van Assche
2021-05-04 7:29 ` [PATCH V4 0/4] blk-mq: fix request UAF related with iterating over tagset requests Ming Lei
2021-05-04 10:15 ` John Garry
2021-05-04 11:43 ` Ming Lei
2021-05-05 11:19 ` John Garry
2021-05-05 14:28 ` Ming Lei
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