From 5fd7a84a09e640016fe106dd3e992f5210e23dc7 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 16 Jun 2022 09:43:59 +0800 Subject: blk-mq: protect q->elevator by ->sysfs_lock in blk_mq_elv_switch_none 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 Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20220616014401.817001-2-ming.lei@redhat.com Signed-off-by: Jens Axboe --- block/blk-mq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'block') diff --git a/block/blk-mq.c b/block/blk-mq.c index 26a7f802d7ee..c13d03b2e17c 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -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 -- cgit v1.2.3