usbnet:fix NPE during rx_complete

In the Linux kernel, the following vulnerability has been resolved:

usbnet:fix NPE during rx_complete

Missing usbnet_going_away Check in Critical Path.

The usb_submit_urb function lacks a usbnet_going_away

validation, whereas __usbnet_queue_skb includes this check.

This inconsistency creates a race condition where:

A URB request may succeed, but the corresponding SKB data

fails to be queued.

Subsequent processes:

(e.g., rx_complete → defer_bh → __skb_unlink(skb, list))

attempt to access skb->next, triggering a NULL pointer

dereference (Kernel Panic).