5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei <ming.lei@xxxxxxxxxx> 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@xxxxxxxxxxxxxxx> Reported-by: Zhong Jinghua <zhongjinghua@xxxxxxxxxx> Link: https://lore.kernel.org/linux-block/Y5prfOjyyjQKUrtH@T590/T/#u Link: https://lore.kernel.org/lkml/Y4%2FmzMd4evRg9yDi@fedora/ Cc: Hillf Danton <hdanton@xxxxxxxx> Cc: Yu Kuai <yukuai3@xxxxxxxxxx> Cc: Dennis Zhou <dennis@xxxxxxxxxx> Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path") Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221215021629.74870-1-ming.lei@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Saranya Muruganandam <saranyamohan@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -405,8 +405,6 @@ 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 @@ -748,6 +748,8 @@ 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); }
