static struct sk_buff *compose_sadb_supported(const struct sadb_msg *orig,
					      gfp_t allocation)
{
	struct sk_buff *skb;
	struct sadb_msg *hdr;
	int len, auth_len, enc_len, i;

	auth_len = xfrm_count_pfkey_auth_supported();
	if (auth_len) {
		auth_len *= sizeof(struct sadb_alg);
		auth_len += sizeof(struct sadb_supported);
	}

	enc_len = xfrm_count_pfkey_enc_supported();
	if (enc_len) {
		enc_len *= sizeof(struct sadb_alg);
		enc_len += sizeof(struct sadb_supported);
	}

	len = enc_len + auth_len + sizeof(struct sadb_msg);

	skb = alloc_skb(len + 16, allocation);
	if (!skb)
		goto out_put_algs;

	hdr = (struct sadb_msg *) skb_put(skb, sizeof(*hdr));
	pfkey_hdr_dup(hdr, orig);
	hdr->sadb_msg_errno = 0;
	hdr->sadb_msg_len = len / sizeof(uint64_t);

	if (auth_len) {
		struct sadb_supported *sp;
		struct sadb_alg *ap;

		sp = (struct sadb_supported *) skb_put(skb, auth_len);
		ap = (struct sadb_alg *) (sp + 1);

		sp->sadb_supported_len = auth_len / sizeof(uint64_t);
		sp->sadb_supported_exttype = SADB_EXT_SUPPORTED_AUTH;

		for (i = 0; ; i++) {
			struct xfrm_algo_desc *aalg = xfrm_aalg_get_byidx(i);
			if (!aalg)
				break;
			if (!aalg->pfkey_supported)
				continue;
			if (aalg->available)
				*ap++ = aalg->desc;
		}
	}

	if (enc_len) {
		struct sadb_supported *sp;
		struct sadb_alg *ap;

		sp = (struct sadb_supported *) skb_put(skb, enc_len);
		ap = (struct sadb_alg *) (sp + 1);

		sp->sadb_supported_len = enc_len / sizeof(uint64_t);
		sp->sadb_supported_exttype = SADB_EXT_SUPPORTED_ENCRYPT;

		for (i = 0; ; i++) {
			struct xfrm_algo_desc *ealg = xfrm_ealg_get_byidx(i);
			if (!ealg)
				break;
			if (!ealg->pfkey_supported)
				continue;
			if (ealg->available)
				*ap++ = ealg->desc;
		}
	}

out_put_algs:
	return skb;
}

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.