void dev_close_many(struct list_head *head, bool unlink)
{
	struct net_device *dev, *tmp;

	/* Remove the devices that don't need to be closed */
	list_for_each_entry_safe(dev, tmp, head, close_list)
		if (!(dev->flags & IFF_UP))
			list_del_init(&dev->close_list);

	__dev_close_many(head);

	list_for_each_entry_safe(dev, tmp, head, close_list) {
		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
		call_netdevice_notifiers(NETDEV_DOWN, dev);
		if (unlink)
			list_del_init(&dev->close_list);
	}
}

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