static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
				       char __user *optval, int __user *optlen)
{
	struct sctp_bind_addr *bp;
	struct sctp_association *asoc;
	int cnt = 0;
	struct sctp_getaddrs getaddrs;
	struct sctp_sockaddr_entry *addr;
	void __user *to;
	union sctp_addr temp;
	struct sctp_sock *sp = sctp_sk(sk);
	int addrlen;
	int err = 0;
	size_t space_left;
	int bytes_copied = 0;
	void *addrs;
	void *buf;

	if (len < sizeof(struct sctp_getaddrs))
		return -EINVAL;

	if (copy_from_user(&getaddrs, optval, sizeof(struct sctp_getaddrs)))
		return -EFAULT;

	/*
	 *  For UDP-style sockets, id specifies the association to query.
	 *  If the id field is set to the value '0' then the locally bound
	 *  addresses are returned without regard to any particular
	 *  association.
	 */
	if (0 == getaddrs.assoc_id) {
		bp = &sctp_sk(sk)->ep->base.bind_addr;
	} else {
		asoc = sctp_id2assoc(sk, getaddrs.assoc_id);
		if (!asoc)
			return -EINVAL;
		bp = &asoc->base.bind_addr;
	}

	to = optval + offsetof(struct sctp_getaddrs, addrs);
	space_left = len - offsetof(struct sctp_getaddrs, addrs);

	addrs = kmalloc(space_left, GFP_USER | __GFP_NOWARN);
	if (!addrs)
		return -ENOMEM;

	/* If the endpoint is bound to 0.0.0.0 or ::0, get the valid
	 * addresses from the global local address list.
	 */
	if (sctp_list_single_entry(&bp->address_list)) {
		addr = list_entry(bp->address_list.next,
				  struct sctp_sockaddr_entry, list);
		if (sctp_is_any(sk, &addr->a)) {
			cnt = sctp_copy_laddrs(sk, bp->port, addrs,
						space_left, &bytes_copied);
			if (cnt < 0) {
				err = cnt;
				goto out;
			}
			goto copy_getaddrs;
		}
	}

	buf = addrs;
	/* Protection on the bound address list is not needed since
	 * in the socket option context we hold a socket lock and
	 * thus the bound address list can't change.
	 */
	list_for_each_entry(addr, &bp->address_list, list) {
		memcpy(&temp, &addr->a, sizeof(temp));
		addrlen = sctp_get_pf_specific(sk->sk_family)
			      ->addr_to_user(sp, &temp);
		if (space_left < addrlen) {
			err =  -ENOMEM; /*fixme: right error?*/
			goto out;
		}
		memcpy(buf, &temp, addrlen);
		buf += addrlen;
		bytes_copied += addrlen;
		cnt++;
		space_left -= addrlen;
	}

copy_getaddrs:
	if (copy_to_user(to, addrs, bytes_copied)) {
		err = -EFAULT;
		goto out;
	}
	if (put_user(cnt, &((struct sctp_getaddrs __user *)optval)->addr_num)) {
		err = -EFAULT;
		goto out;
	}
	if (put_user(bytes_copied, optlen))
		err = -EFAULT;
out:
	kfree(addrs);
	return err;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.