5.10-stable review patch. If anyone has any objections, please let me know.
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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.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/blk-core.c | 2 -- block/blk-sysfs.c | 2 ++ 2 files changed, 2 insertions(+), 2 deletions(-)
--- a/block/blk-core.c +++ b/block/blk-core.c @@ -414,8 +414,6 @@ void blk_cleanup_queue(struct request_qu blk_mq_sched_free_requests(q); mutex_unlock(&q->sysfs_lock);
- percpu_ref_exit(&q->q_usage_counter); - /* @q is and will stay empty, shutdown and put */ blk_put_queue(q); } --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -726,6 +726,8 @@ static void blk_free_queue_rcu(struct rc { 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); }