rndis_wlan: add return value validation

Function create_singlethread_workqueue() will return a NULL pointer if
there is no enough memory, and its return value should be validated
before using. However, in function rndis_wlan_bind(), its return value
is not checked. This may cause NULL dereference bugs. This patch fixes
it.
Signed-off-by: NPan Bian <bianpan2016@163.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/rndis_wlan.c

@@ -3428,6 +3428,10 @@ static int rndis_wlan_bind(struct usbnet *usbdev, struct usb_interface *intf)
 
 	/* because rndis_command() sleeps we need to use workqueue */
 	priv->workqueue = create_singlethread_workqueue("rndis_wlan");
+	if (!priv->workqueue) {
+		wiphy_free(wiphy);
+		return -ENOMEM;
+	}
 	INIT_WORK(&priv->work, rndis_wlan_worker);
 	INIT_DELAYED_WORK(&priv->dev_poller_work, rndis_device_poller);
 	INIT_DELAYED_WORK(&priv->scan_work, rndis_get_scan_results);