From: Ming Lei ming.lei@redhat.com

commit d36a9ea5e7766961e753ee38d4c331bbe6ef659b upstream.

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.

Backport-notes: Not a clean cherry-pick since a lot has changed, however essentially the same fix.

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: 2b0d3d3e4fcf ("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 Signed-off-by: Saranya Muruganandam saranyamohan@google.com --- block/blk-sysfs.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index a582ea0da74f..a82bdec923b2 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -737,6 +737,7 @@ static void blk_free_queue_rcu(struct rcu_head *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_get_queue_kmem_cache(blk_queue_has_srcu(q)), q); }

@@ -762,8 +763,6 @@ static void blk_release_queue(struct kobject *kobj)

might_sleep();

- 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);