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blk-mq: protect q->elevator by ->sysfs_lock in blk_mq_elv_switch_none

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elevator can be tore down by sysfs switch interface or disk release, so
hold ->sysfs_lock before referring to q->elevator, then potential
use-after-free can be avoided.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220616014401.817001-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2022-06-16 09:43:59 +08:00 committed by Jens Axboe
parent 14dc7a18ab
commit 5fd7a84a09
1 changed files with 3 additions and 1 deletions
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4
block/blk-mq.c
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@ -4440,12 +4440,14 @@ static bool blk_mq_elv_switch_none(struct list_head *head,
if (!qe)
return false;
/* q->elevator needs protection from ->sysfs_lock */
mutex_lock(&q->sysfs_lock);
INIT_LIST_HEAD(&qe->node);
qe->q = q;
qe->type = q->elevator->type;
list_add(&qe->node, head);
mutex_lock(&q->sysfs_lock);
/*
* After elevator_switch_mq, the previous elevator_queue will be
* released by elevator_release. The reference of the io scheduler