static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
				struct flowi *fl, struct sock *sk)
{
	struct sctp_association *asoc = t->asoc;
	struct rtable *rt;
	struct flowi4 *fl4 = &fl->u.ip4;
	struct sctp_bind_addr *bp;
	struct sctp_sockaddr_entry *laddr;
	struct dst_entry *dst = NULL;
	union sctp_addr *daddr = &t->ipaddr;
	union sctp_addr dst_saddr;

	memset(fl4, 0x0, sizeof(struct flowi4));
	fl4->daddr  = daddr->v4.sin_addr.s_addr;
	fl4->fl4_dport = daddr->v4.sin_port;
	fl4->flowi4_proto = IPPROTO_SCTP;
	if (asoc) {
		fl4->flowi4_tos = RT_CONN_FLAGS(asoc->base.sk);
		fl4->flowi4_oif = asoc->base.sk->sk_bound_dev_if;
		fl4->fl4_sport = htons(asoc->base.bind_addr.port);
	}
	if (saddr) {
		fl4->saddr = saddr->v4.sin_addr.s_addr;
		fl4->fl4_sport = saddr->v4.sin_port;
	}

	pr_debug("%s: dst:%pI4, src:%pI4 - ", __func__, &fl4->daddr,
		 &fl4->saddr);

	rt = ip_route_output_key(sock_net(sk), fl4);
	if (!IS_ERR(rt))
		dst = &rt->dst;

	/* If there is no association or if a source address is passed, no
	 * more validation is required.
	 */
	if (!asoc || saddr)
		goto out;

	bp = &asoc->base.bind_addr;

	if (dst) {
		/* Walk through the bind address list and look for a bind
		 * address that matches the source address of the returned dst.
		 */
		sctp_v4_dst_saddr(&dst_saddr, fl4, htons(bp->port));
		rcu_read_lock();
		list_for_each_entry_rcu(laddr, &bp->address_list, list) {
			if (!laddr->valid || (laddr->state == SCTP_ADDR_DEL) ||
			    (laddr->state != SCTP_ADDR_SRC &&
			    !asoc->src_out_of_asoc_ok))
				continue;
			if (sctp_v4_cmp_addr(&dst_saddr, &laddr->a))
				goto out_unlock;
		}
		rcu_read_unlock();

		/* None of the bound addresses match the source address of the
		 * dst. So release it.
		 */
		dst_release(dst);
		dst = NULL;
	}

	/* Walk through the bind address list and try to get a dst that
	 * matches a bind address as the source address.
	 */
	rcu_read_lock();
	list_for_each_entry_rcu(laddr, &bp->address_list, list) {
		struct net_device *odev;

		if (!laddr->valid)
			continue;
		if (laddr->state != SCTP_ADDR_SRC ||
		    AF_INET != laddr->a.sa.sa_family)
			continue;

		fl4->fl4_sport = laddr->a.v4.sin_port;
		flowi4_update_output(fl4,
				     asoc->base.sk->sk_bound_dev_if,
				     RT_CONN_FLAGS(asoc->base.sk),
				     daddr->v4.sin_addr.s_addr,
				     laddr->a.v4.sin_addr.s_addr);

		rt = ip_route_output_key(sock_net(sk), fl4);
		if (IS_ERR(rt))
			continue;

		if (!dst)
			dst = &rt->dst;

		/* Ensure the src address belongs to the output
		 * interface.
		 */
		odev = __ip_dev_find(sock_net(sk), laddr->a.v4.sin_addr.s_addr,
				     false);
		if (!odev || odev->ifindex != fl4->flowi4_oif) {
			if (&rt->dst != dst)
				dst_release(&rt->dst);
			continue;
		}

		if (dst != &rt->dst)
			dst_release(dst);
		dst = &rt->dst;
		break;
	}

out_unlock:
	rcu_read_unlock();
out:
	t->dst = dst;
	if (dst)
		pr_debug("rt_dst:%pI4, rt_src:%pI4\n",
			 &fl4->daddr, &fl4->saddr);
	else
		pr_debug("no route\n");
}

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.