nvmet-rdma: fix use-after-free when a port is removed

When removing a port, all its controllers are being removed, but there
are queues on the port that doesn't belong to any controller (during
connection time). This causes a use-after-free bug for any command
that dereferences req->port (like in nvmet_alloc_ctrl). Those queues
should be destroyed before freeing the port via configfs. Destroy the
remaining queues after the RDMA-CM was destroyed guarantees that no
new queue will be created.
Signed-off-by: Israel Rukshin <israelr@nvidia.com>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/rdma.c

@@ -1819,12 +1819,36 @@ static void nvmet_rdma_delete_ctrl(struct nvmet_ctrl *ctrl)
 	mutex_unlock(&nvmet_rdma_queue_mutex);
 }
 
+static void nvmet_rdma_destroy_port_queues(struct nvmet_rdma_port *port)
+{
+	struct nvmet_rdma_queue *queue, *tmp;
+	struct nvmet_port *nport = port->nport;
+
+	mutex_lock(&nvmet_rdma_queue_mutex);
+	list_for_each_entry_safe(queue, tmp, &nvmet_rdma_queue_list,
+				 queue_list) {
+		if (queue->port != nport)
+			continue;
+
+		list_del_init(&queue->queue_list);
+		__nvmet_rdma_queue_disconnect(queue);
+	}
+	mutex_unlock(&nvmet_rdma_queue_mutex);
+}
+
 static void nvmet_rdma_disable_port(struct nvmet_rdma_port *port)
 {
 	struct rdma_cm_id *cm_id = xchg(&port->cm_id, NULL);
 
 	if (cm_id)
 		rdma_destroy_id(cm_id);
+
+	/*
+	 * Destroy the remaining queues, which are not belong to any
+	 * controller yet. Do it here after the RDMA-CM was destroyed
+	 * guarantees that no new queue will be created.
+	 */
+	nvmet_rdma_destroy_port_queues(port);
 }
 
 static int nvmet_rdma_enable_port(struct nvmet_rdma_port *port)