Messages in this thread Patch in this message | | | From | Akinobu Mita <> | Subject | [PATCH v4 3/7] blk-mq: Fix use after of free q->mq_map | Date | Sun, 27 Sep 2015 02:09:21 +0900 |
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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: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <tom.leiming@gmail.com> Cc: Christoph Hellwig <hch@lst.de> --- block/blk-mq.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)
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 @@ 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); -- 1.9.1
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