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* [PATCH] block: fix use-after-free of q->q_usage_counter
@ 2023-09-21 18:20 Saranya Muruganandam
  2023-09-21 20:32 ` kernel test robot
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Saranya Muruganandam @ 2023-09-21 18:20 UTC (permalink / raw)
  To: Jens Axboe, Tejun Heo, Ming Lei, stable
  Cc: linux-block, linux-kernel, Zhang Wensheng, Zhong Jinghua,
	Hillf Danton, Yu Kuai, Dennis Zhou, Saranya Muruganandam

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-core.c  | 2 --
 block/blk-sysfs.c | 2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index d0d0dd8151f7..e5eeec801f56 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -414,8 +414,6 @@ void blk_cleanup_queue(struct request_queue *q)
 		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);
 }
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 8c5816364dd1..9174137a913c 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);
 }
 
-- 
2.42.0.515.g380fc7ccd1-goog


^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2023-10-07 10:22 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-09-21 18:20 [PATCH] block: fix use-after-free of q->q_usage_counter Saranya Muruganandam
2023-09-21 20:32 ` kernel test robot
2023-09-22  1:09 ` Ming Lei
2023-09-22  9:26 ` Greg KH
2023-09-22 18:21   ` Saranya Muruganandam
2023-10-07 10:22     ` Greg KH

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