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>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0262131..92648d8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1925,6 +1925,9 @@
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 @@
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);