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>
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@ -1925,6 +1925,9 @@ void blk_mq_release(struct request_queue *q)
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kfree(hctx);
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}
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kfree(q->mq_map);
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q->mq_map = NULL;
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kfree(q->queue_hw_ctx);
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/* ctx kobj stays in queue_ctx */
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@ -2070,11 +2073,6 @@ void blk_mq_free_queue(struct request_queue *q)
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blk_mq_free_hw_queues(q, set);
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percpu_ref_exit(&q->mq_usage_counter);
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kfree(q->mq_map);
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q->mq_map = NULL;
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mutex_lock(&all_q_mutex);
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list_del_init(&q->all_q_node);
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mutex_unlock(&all_q_mutex);
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