int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
			  struct sk_buff *skb, unsigned header_len)
{
	struct scatterlist sg;
	const struct tcphdr *tp = tcp_hdr(skb);
	struct hash_desc *desc = &hp->md5_desc;
	unsigned i;
	const unsigned head_data_len = skb_headlen(skb) > header_len ?
				       skb_headlen(skb) - header_len : 0;
	const struct skb_shared_info *shi = skb_shinfo(skb);

	sg_init_table(&sg, 1);

	sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
	if (crypto_hash_update(desc, &sg, head_data_len))
		return 1;

	for (i = 0; i < shi->nr_frags; ++i) {
		const struct skb_frag_struct *f = &shi->frags[i];
		sg_set_page(&sg, f->page, f->size, f->page_offset);
		if (crypto_hash_update(desc, &sg, f->size))
			return 1;
	}

	return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.