static noinline_for_stack int ethtool_get_rxnfc(struct net_device *dev,
						void __user *useraddr)
{
	struct ethtool_rxnfc info;
	const struct ethtool_ops *ops = dev->ethtool_ops;
	int ret;
	void *rule_buf = NULL;

	if (!ops->get_rxnfc)
		return -EOPNOTSUPP;

	if (copy_from_user(&info, useraddr, sizeof(info)))
		return -EFAULT;

	if (info.cmd == ETHTOOL_GRXCLSRLALL) {
		if (info.rule_cnt > 0) {
			rule_buf = kmalloc(info.rule_cnt * sizeof(u32),
					   GFP_USER);
			if (!rule_buf)
				return -ENOMEM;
		}
	}

	ret = ops->get_rxnfc(dev, &info, rule_buf);
	if (ret < 0)
		goto err_out;

	ret = -EFAULT;
	if (copy_to_user(useraddr, &info, sizeof(info)))
		goto err_out;

	if (rule_buf) {
		useraddr += offsetof(struct ethtool_rxnfc, rule_locs);
		if (copy_to_user(useraddr, rule_buf,
				 info.rule_cnt * sizeof(u32)))
			goto err_out;
	}
	ret = 0;

err_out:
	kfree(rule_buf);

	return ret;
}
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.