wifi: plfxlc: check for allocation failure in plfxlc_usb_wreq_async()

Check for if the usb_alloc_urb() failed.

Fixes: 68d57a07 ("wireless: add plfxlc driver for pureLiFi X, XL, XC devices")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/e8d4a19a-f251-4101-a89b-607345e938cb@moroto.mountain

drivers/net/wireless/purelifi/plfxlc/usb.c

@@ -493,9 +493,12 @@ int plfxlc_usb_wreq_async(struct plfxlc_usb *usb, const u8 *buffer,
 			  void *context)
 {
 	struct usb_device *udev = interface_to_usbdev(usb->ez_usb);
-	struct urb *urb = usb_alloc_urb(0, GFP_ATOMIC);
+	struct urb *urb;
 	int r;
 
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb)
+		return -ENOMEM;
 	usb_fill_bulk_urb(urb, udev, usb_sndbulkpipe(udev, EP_DATA_OUT),
 			  (void *)buffer, buffer_len, complete_fn, context);