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block: fix use-after-free of q->q_usage_counter

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For blk-mq, queue release handler is usually called after
blk_mq_freeze_queue_wait() returns. However, the
q_usage_counter->release() handler may not be run yet at that time, so
this can cause a use-after-free.

Fix the issue by moving percpu_ref_exit() into blk_free_queue_rcu().
Since ->release() is called with rcu read lock held, it is agreed that
the race should be covered in caller per discussion from the two links.

Reported-by: Zhang Wensheng <zhangwensheng@huaweicloud.com>
Reported-by: Zhong Jinghua <zhongjinghua@huawei.com>
Link: https://lore.kernel.org/linux-block/Y5prfOjyyjQKUrtH@T590/T/#u
Link: https://lore.kernel.org/lkml/Y4%2FmzMd4evRg9yDi@fedora/
Cc: Hillf Danton <hdanton@sina.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Cc: Dennis Zhou <dennis@kernel.org>
Fixes: 2b0d3d3e4f ("percpu_ref: reduce memory footprint of percpu_ref in fast path")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20221215021629.74870-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2022-12-15 10:16:29 +08:00 committed by Jens Axboe
parent 1eb206208b
commit d36a9ea5e7
1 changed files with 5 additions and 4 deletions
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9
block/blk-core.c
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@ -254,14 +254,15 @@ EXPORT_SYMBOL_GPL(blk_clear_pm_only);
static void blk_free_queue_rcu(struct rcu_head *rcu_head)
{
kmem_cache_free(blk_requestq_cachep,
container_of(rcu_head, struct request_queue, rcu_head));
struct request_queue *q = container_of(rcu_head,
struct request_queue, rcu_head);
percpu_ref_exit(&q->q_usage_counter);
kmem_cache_free(blk_requestq_cachep, q);
}
static void blk_free_queue(struct request_queue *q)
{
percpu_ref_exit(&q->q_usage_counter);
if (q->poll_stat)
blk_stat_remove_callback(q, q->poll_cb);
blk_stat_free_callback(q->poll_cb);