static int sctp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
			int noblock, int flags, int *addr_len)
{
	struct sctp_ulpevent *event = NULL;
	struct sctp_sock *sp = sctp_sk(sk);
	struct sk_buff *skb, *head_skb;
	int copied;
	int err = 0;
	int skb_len;

	pr_debug("%s: sk:%p, msghdr:%p, len:%zd, noblock:%d, flags:0x%x, "
		 "addr_len:%p)\n", __func__, sk, msg, len, noblock, flags,
		 addr_len);

	lock_sock(sk);

	if (sctp_style(sk, TCP) && !sctp_sstate(sk, ESTABLISHED) &&
	    !sctp_sstate(sk, CLOSING) && !sctp_sstate(sk, CLOSED)) {
		err = -ENOTCONN;
		goto out;
	}

	skb = sctp_skb_recv_datagram(sk, flags, noblock, &err);
	if (!skb)
		goto out;

	/* Get the total length of the skb including any skb's in the
	 * frag_list.
	 */
	skb_len = skb->len;

	copied = skb_len;
	if (copied > len)
		copied = len;

	err = skb_copy_datagram_msg(skb, 0, msg, copied);

	event = sctp_skb2event(skb);

	if (err)
		goto out_free;

	if (event->chunk && event->chunk->head_skb)
		head_skb = event->chunk->head_skb;
	else
		head_skb = skb;
	sock_recv_ts_and_drops(msg, sk, head_skb);
	if (sctp_ulpevent_is_notification(event)) {
		msg->msg_flags |= MSG_NOTIFICATION;
		sp->pf->event_msgname(event, msg->msg_name, addr_len);
	} else {
		sp->pf->skb_msgname(head_skb, msg->msg_name, addr_len);
	}

	/* Check if we allow SCTP_NXTINFO. */
	if (sp->recvnxtinfo)
		sctp_ulpevent_read_nxtinfo(event, msg, sk);
	/* Check if we allow SCTP_RCVINFO. */
	if (sp->recvrcvinfo)
		sctp_ulpevent_read_rcvinfo(event, msg);
	/* Check if we allow SCTP_SNDRCVINFO. */
	if (sp->subscribe.sctp_data_io_event)
		sctp_ulpevent_read_sndrcvinfo(event, msg);

	err = copied;

	/* If skb's length exceeds the user's buffer, update the skb and
	 * push it back to the receive_queue so that the next call to
	 * recvmsg() will return the remaining data. Don't set MSG_EOR.
	 */
	if (skb_len > copied) {
		msg->msg_flags &= ~MSG_EOR;
		if (flags & MSG_PEEK)
			goto out_free;
		sctp_skb_pull(skb, copied);
		skb_queue_head(&sk->sk_receive_queue, skb);

		/* When only partial message is copied to the user, increase
		 * rwnd by that amount. If all the data in the skb is read,
		 * rwnd is updated when the event is freed.
		 */
		if (!sctp_ulpevent_is_notification(event))
			sctp_assoc_rwnd_increase(event->asoc, copied);
		goto out;
	} else if ((event->msg_flags & MSG_NOTIFICATION) ||
		   (event->msg_flags & MSG_EOR))
		msg->msg_flags |= MSG_EOR;
	else
		msg->msg_flags &= ~MSG_EOR;

out_free:
	if (flags & MSG_PEEK) {
		/* Release the skb reference acquired after peeking the skb in
		 * sctp_skb_recv_datagram().
		 */
		kfree_skb(skb);
	} else {
		/* Free the event which includes releasing the reference to
		 * the owner of the skb, freeing the skb and updating the
		 * rwnd.
		 */
		sctp_ulpevent_free(event);
	}
out:
	release_sock(sk);
	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.