From 3a651d39d0fc89305f4fb0c6399ad9c93e76add4 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Wed, 29 Mar 2023 11:20:08 +0800 Subject: [PATCH] block: fix use-after-free of q->q_usage_counter mainline inclusion from mainline-v6.2-rc1 commit d36a9ea5e7766961e753ee38d4c331bbe6ef659b category: bugfix bugzilla: 187268, https://gitee.com/openeuler/kernel/issues/I5N162 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d36a9ea5e7766961e753ee38d4c331bbe6ef659b ---------------------------------------- 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 Reported-by: Zhong Jinghua Link: https://lore.kernel.org/linux-block/Y5prfOjyyjQKUrtH@T590/T/#u Link: https://lore.kernel.org/lkml/Y4%2FmzMd4evRg9yDi@fedora/ Cc: Hillf Danton Cc: Yu Kuai Cc: Dennis Zhou Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path") Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20221215021629.74870-1-ming.lei@redhat.com Signed-off-by: Jens Axboe conflicts: block/blk-sysfs.c block/blk-core.c Signed-off-by: Zhong Jinghua Reviewed-by: Hou Tao Signed-off-by: Jialin Zhang --- block/blk-sysfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 35cd1df55680..169e63ee05cb 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -726,6 +726,8 @@ 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_requestq_cachep, q); } @@ -784,8 +786,6 @@ static void blk_release_queue(struct kobject *kobj) might_sleep(); - percpu_ref_exit(&q->q_usage_counter); - if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags)) blk_stat_remove_callback(q, q->poll_cb); blk_stat_free_callback(q->poll_cb); -- GitLab