nvme-rdma: fix possible use-after-free in connect timeout

If the connect times out, we may have already destroyed the
queue in the timeout handler, so test if the queue is still
allocated in the connect error handler.
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

drivers/nvme/host/rdma.c

@@ -620,7 +620,8 @@ static int nvme_rdma_start_queue(struct nvme_rdma_ctrl *ctrl, int idx)
 	if (!ret) {
 		set_bit(NVME_RDMA_Q_LIVE, &queue->flags);
 	} else {
-		__nvme_rdma_stop_queue(queue);
+		if (test_bit(NVME_RDMA_Q_ALLOCATED, &queue->flags))
+			__nvme_rdma_stop_queue(queue);
 		dev_info(ctrl->ctrl.device,
 			"failed to connect queue: %d ret=%d\n", idx, ret);
 	}