static int pfkey_xfrm_policy2msg(struct sk_buff *skb, const struct xfrm_policy *xp, int dir)
{
	struct sadb_msg *hdr;
	struct sadb_address *addr;
	struct sadb_lifetime *lifetime;
	struct sadb_x_policy *pol;
	struct sadb_x_sec_ctx *sec_ctx;
	struct xfrm_sec_ctx *xfrm_ctx;
	int i;
	int size;
	int sockaddr_size = pfkey_sockaddr_size(xp->family);
	int socklen = pfkey_sockaddr_len(xp->family);

	size = pfkey_xfrm_policy2msg_size(xp);

	/* call should fill header later */
	hdr = (struct sadb_msg *) skb_put(skb, sizeof(struct sadb_msg));
	memset(hdr, 0, size);	/* XXX do we need this ? */

	/* src address */
	addr = (struct sadb_address*) skb_put(skb,
					      sizeof(struct sadb_address)+sockaddr_size);
	addr->sadb_address_len =
		(sizeof(struct sadb_address)+sockaddr_size)/
			sizeof(uint64_t);
	addr->sadb_address_exttype = SADB_EXT_ADDRESS_SRC;
	addr->sadb_address_proto = pfkey_proto_from_xfrm(xp->selector.proto);
	addr->sadb_address_prefixlen = xp->selector.prefixlen_s;
	addr->sadb_address_reserved = 0;
	if (!pfkey_sockaddr_fill(&xp->selector.saddr,
				 xp->selector.sport,
				 (struct sockaddr *) (addr + 1),
				 xp->family))
		BUG();

	/* dst address */
	addr = (struct sadb_address*) skb_put(skb,
					      sizeof(struct sadb_address)+sockaddr_size);
	addr->sadb_address_len =
		(sizeof(struct sadb_address)+sockaddr_size)/
			sizeof(uint64_t);
	addr->sadb_address_exttype = SADB_EXT_ADDRESS_DST;
	addr->sadb_address_proto = pfkey_proto_from_xfrm(xp->selector.proto);
	addr->sadb_address_prefixlen = xp->selector.prefixlen_d;
	addr->sadb_address_reserved = 0;

	pfkey_sockaddr_fill(&xp->selector.daddr, xp->selector.dport,
			    (struct sockaddr *) (addr + 1),
			    xp->family);

	/* hard time */
	lifetime = (struct sadb_lifetime *)  skb_put(skb,
						     sizeof(struct sadb_lifetime));
	lifetime->sadb_lifetime_len =
		sizeof(struct sadb_lifetime)/sizeof(uint64_t);
	lifetime->sadb_lifetime_exttype = SADB_EXT_LIFETIME_HARD;
	lifetime->sadb_lifetime_allocations =  _X2KEY(xp->lft.hard_packet_limit);
	lifetime->sadb_lifetime_bytes = _X2KEY(xp->lft.hard_byte_limit);
	lifetime->sadb_lifetime_addtime = xp->lft.hard_add_expires_seconds;
	lifetime->sadb_lifetime_usetime = xp->lft.hard_use_expires_seconds;
	/* soft time */
	lifetime = (struct sadb_lifetime *)  skb_put(skb,
						     sizeof(struct sadb_lifetime));
	lifetime->sadb_lifetime_len =
		sizeof(struct sadb_lifetime)/sizeof(uint64_t);
	lifetime->sadb_lifetime_exttype = SADB_EXT_LIFETIME_SOFT;
	lifetime->sadb_lifetime_allocations =  _X2KEY(xp->lft.soft_packet_limit);
	lifetime->sadb_lifetime_bytes = _X2KEY(xp->lft.soft_byte_limit);
	lifetime->sadb_lifetime_addtime = xp->lft.soft_add_expires_seconds;
	lifetime->sadb_lifetime_usetime = xp->lft.soft_use_expires_seconds;
	/* current time */
	lifetime = (struct sadb_lifetime *)  skb_put(skb,
						     sizeof(struct sadb_lifetime));
	lifetime->sadb_lifetime_len =
		sizeof(struct sadb_lifetime)/sizeof(uint64_t);
	lifetime->sadb_lifetime_exttype = SADB_EXT_LIFETIME_CURRENT;
	lifetime->sadb_lifetime_allocations = xp->curlft.packets;
	lifetime->sadb_lifetime_bytes = xp->curlft.bytes;
	lifetime->sadb_lifetime_addtime = xp->curlft.add_time;
	lifetime->sadb_lifetime_usetime = xp->curlft.use_time;

	pol = (struct sadb_x_policy *)  skb_put(skb, sizeof(struct sadb_x_policy));
	pol->sadb_x_policy_len = sizeof(struct sadb_x_policy)/sizeof(uint64_t);
	pol->sadb_x_policy_exttype = SADB_X_EXT_POLICY;
	pol->sadb_x_policy_type = IPSEC_POLICY_DISCARD;
	if (xp->action == XFRM_POLICY_ALLOW) {
		if (xp->xfrm_nr)
			pol->sadb_x_policy_type = IPSEC_POLICY_IPSEC;
		else
			pol->sadb_x_policy_type = IPSEC_POLICY_NONE;
	}
	pol->sadb_x_policy_dir = dir+1;
	pol->sadb_x_policy_id = xp->index;
	pol->sadb_x_policy_priority = xp->priority;

	for (i=0; i<xp->xfrm_nr; i++) {
		const struct xfrm_tmpl *t = xp->xfrm_vec + i;
		struct sadb_x_ipsecrequest *rq;
		int req_size;
		int mode;

		req_size = sizeof(struct sadb_x_ipsecrequest);
		if (t->mode == XFRM_MODE_TUNNEL) {
			socklen = pfkey_sockaddr_len(t->encap_family);
			req_size += socklen * 2;
		} else {
			size -= 2*socklen;
		}
		rq = (void*)skb_put(skb, req_size);
		pol->sadb_x_policy_len += req_size/8;
		memset(rq, 0, sizeof(*rq));
		rq->sadb_x_ipsecrequest_len = req_size;
		rq->sadb_x_ipsecrequest_proto = t->id.proto;
		if ((mode = pfkey_mode_from_xfrm(t->mode)) < 0)
			return -EINVAL;
		rq->sadb_x_ipsecrequest_mode = mode;
		rq->sadb_x_ipsecrequest_level = IPSEC_LEVEL_REQUIRE;
		if (t->reqid)
			rq->sadb_x_ipsecrequest_level = IPSEC_LEVEL_UNIQUE;
		if (t->optional)
			rq->sadb_x_ipsecrequest_level = IPSEC_LEVEL_USE;
		rq->sadb_x_ipsecrequest_reqid = t->reqid;

		if (t->mode == XFRM_MODE_TUNNEL) {
			u8 *sa = (void *)(rq + 1);
			pfkey_sockaddr_fill(&t->saddr, 0,
					    (struct sockaddr *)sa,
					    t->encap_family);
			pfkey_sockaddr_fill(&t->id.daddr, 0,
					    (struct sockaddr *) (sa + socklen),
					    t->encap_family);
		}
	}

	/* security context */
	if ((xfrm_ctx = xp->security)) {
		int ctx_size = pfkey_xfrm_policy2sec_ctx_size(xp);

		sec_ctx = (struct sadb_x_sec_ctx *) skb_put(skb, ctx_size);
		sec_ctx->sadb_x_sec_len = ctx_size / sizeof(uint64_t);
		sec_ctx->sadb_x_sec_exttype = SADB_X_EXT_SEC_CTX;
		sec_ctx->sadb_x_ctx_doi = xfrm_ctx->ctx_doi;
		sec_ctx->sadb_x_ctx_alg = xfrm_ctx->ctx_alg;
		sec_ctx->sadb_x_ctx_len = xfrm_ctx->ctx_len;
		memcpy(sec_ctx + 1, xfrm_ctx->ctx_str,
		       xfrm_ctx->ctx_len);
	}

	hdr->sadb_msg_len = size / sizeof(uint64_t);
	hdr->sadb_msg_reserved = atomic_read(&xp->refcnt);

	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.