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blk-mq: Fix use after of free q->mq_map 

CPU hotplug handling for blk-mq (blk_mq_queue_reinit) updates
q->mq_map by blk_mq_update_queue_map() for all request queues in
all_q_list.  On the other hand, q->mq_map is released before deleting
the queue from all_q_list.

So if CPU hotplug event occurs in the window, invalid memory access
can happen.  Fix it by releasing q->mq_map in blk_mq_release() to make
it happen latter than removal from all_q_list.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Suggested-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Akinobu Mita 2015-09-27 02:09:21 +09:00 committed by Jens Axboe
parent 4593fdbe7a
commit a723bab3d7
1 changed files with 3 additions and 5 deletions
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8
block/blk-mq.c
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@ -1925,6 +1925,9 @@ void blk_mq_release(struct request_queue *q)
kfree(hctx);
}
kfree(q->mq_map);
q->mq_map = NULL;
kfree(q->queue_hw_ctx);
/* ctx kobj stays in queue_ctx */
@ -2070,11 +2073,6 @@ void blk_mq_free_queue(struct request_queue *q)
blk_mq_free_hw_queues(q, set);
percpu_ref_exit(&q->mq_usage_counter);
kfree(q->mq_map);
q->mq_map = NULL;
mutex_lock(&all_q_mutex);
list_del_init(&q->all_q_node);
mutex_unlock(&all_q_mutex);