static int atrtr_ioctl(unsigned int cmd, void __user *arg)
{
	struct rtentry rt;

	if (copy_from_user(&rt, arg, sizeof(rt)))
		return -EFAULT;

	switch (cmd) {
	case SIOCDELRT:
		if (rt.rt_dst.sa_family != AF_APPLETALK)
			return -EINVAL;
		return atrtr_delete(&((struct sockaddr_at *)
				      &rt.rt_dst)->sat_addr);

	case SIOCADDRT: {
		struct net_device *dev = NULL;
		if (rt.rt_dev) {
			char name[IFNAMSIZ];
			if (copy_from_user(name, rt.rt_dev, IFNAMSIZ-1))
				return -EFAULT;
			name[IFNAMSIZ-1] = '\0';
			dev = __dev_get_by_name(&init_net, name);
			if (!dev)
				return -ENODEV;
		}
		return atrtr_create(&rt, dev);
	}
	}
	return -EINVAL;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.