__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
{
	__sum16 sum;

	sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
	if (likely(!sum)) {
		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
			netdev_rx_csum_fault(skb->dev);
		skb->ip_summed = CHECKSUM_UNNECESSARY;
	}
	return sum;
}

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.