int netdev_set_num_tc(struct net_device *dev, u8 num_tc)
{
	if (num_tc > TC_MAX_QUEUE)
		return -EINVAL;

#ifdef CONFIG_XPS
	netif_reset_xps_queues_gt(dev, 0);
#endif
	dev->num_tc = num_tc;
	return 0;
}

The product dereferences a pointer that it expects to be valid but is NULL.