From: Ming Lei <[email protected]>
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 <[email protected]>
Reported-by: Zhong Jinghua <[email protected]>
Link: https://lore.kernel.org/linux-block/Y5prfOjyyjQKUrtH@T590/T/#u
Link: https://lore.kernel.org/lkml/Y4%2FmzMd4evRg9yDi@fedora/
Cc: Hillf Danton <[email protected]>
Cc: Yu Kuai <[email protected]>
Cc: Dennis Zhou <[email protected]>
Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path")
Signed-off-by: Ming Lei <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Saranya Muruganandam <[email protected]>
---
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);
--
2.42.0.515.g380fc7ccd1-goog