nvme-rdma: avoid request double completion for concurrent nvme_rdma_timeout

A crash happens when inject completing request long time(nearly 30s).
Each name space has a request queue, when inject completing request long
time, multi request queues may have time out requests at the same time,
nvme_rdma_timeout will execute concurrently. Multi requests in different
request queues may be queued in the same rdma queue, multi
nvme_rdma_timeout may call nvme_rdma_stop_queue at the same time.
The first nvme_rdma_timeout will clear NVME_RDMA_Q_LIVE and continue
stopping the rdma queue(drain qp), but the others check NVME_RDMA_Q_LIVE
is already cleared, and then directly complete the requests, complete
request before the qp is fully drained may lead to a use-after-free
condition.

Add a multex lock to serialize nvme_rdma_stop_queue.
Signed-off-by: Chao Leng <lengchao@huawei.com>
Tested-by: Israel Rukshin <israelr@nvidia.com>
Reviewed-by: Israel Rukshin <israelr@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/rdma.c

@@ -97,6 +97,7 @@ struct nvme_rdma_queue {
 	struct completion	cm_done;
 	bool			pi_support;
 	int			cq_size;
+	struct mutex		queue_lock;
 };
 
 struct nvme_rdma_ctrl {
@@ -579,6 +580,7 @@ static int nvme_rdma_alloc_queue(struct nvme_rdma_ctrl *ctrl,
 	int ret;
 
 	queue = &ctrl->queues[idx];
+	mutex_init(&queue->queue_lock);
 	queue->ctrl = ctrl;
 	if (idx && ctrl->ctrl.max_integrity_segments)
 		queue->pi_support = true;
@@ -598,7 +600,8 @@ static int nvme_rdma_alloc_queue(struct nvme_rdma_ctrl *ctrl,
 	if (IS_ERR(queue->cm_id)) {
 		dev_info(ctrl->ctrl.device,
 			"failed to create CM ID: %ld\n", PTR_ERR(queue->cm_id));
-		return PTR_ERR(queue->cm_id);
+		ret = PTR_ERR(queue->cm_id);
+		goto out_destroy_mutex;
 	}
 
 	if (ctrl->ctrl.opts->mask & NVMF_OPT_HOST_TRADDR)
@@ -628,6 +631,8 @@ static int nvme_rdma_alloc_queue(struct nvme_rdma_ctrl *ctrl,
 out_destroy_cm_id:
 	rdma_destroy_id(queue->cm_id);
 	nvme_rdma_destroy_queue_ib(queue);
+out_destroy_mutex:
+	mutex_destroy(&queue->queue_lock);
 	return ret;
 }
 
@@ -639,9 +644,10 @@ static void __nvme_rdma_stop_queue(struct nvme_rdma_queue *queue)
 
 static void nvme_rdma_stop_queue(struct nvme_rdma_queue *queue)
 {
-	if (!test_and_clear_bit(NVME_RDMA_Q_LIVE, &queue->flags))
-		return;
-	__nvme_rdma_stop_queue(queue);
+	mutex_lock(&queue->queue_lock);
+	if (test_and_clear_bit(NVME_RDMA_Q_LIVE, &queue->flags))
+		__nvme_rdma_stop_queue(queue);
+	mutex_unlock(&queue->queue_lock);
 }
 
 static void nvme_rdma_free_queue(struct nvme_rdma_queue *queue)
@@ -651,6 +657,7 @@ static void nvme_rdma_free_queue(struct nvme_rdma_queue *queue)
 
 	nvme_rdma_destroy_queue_ib(queue);
 	rdma_destroy_id(queue->cm_id);
+	mutex_destroy(&queue->queue_lock);
 }
 
 static void nvme_rdma_free_io_queues(struct nvme_rdma_ctrl *ctrl)