static int sctp_setsockopt_events(struct sock *sk, char __user *optval,
				  unsigned int optlen)
{
	struct sctp_association *asoc;
	struct sctp_ulpevent *event;

	if (optlen > sizeof(struct sctp_event_subscribe))
		return -EINVAL;
	if (copy_from_user(&sctp_sk(sk)->subscribe, optval, optlen))
		return -EFAULT;

	/* At the time when a user app subscribes to SCTP_SENDER_DRY_EVENT,
	 * if there is no data to be sent or retransmit, the stack will
	 * immediately send up this notification.
	 */
	if (sctp_ulpevent_type_enabled(SCTP_SENDER_DRY_EVENT,
				       &sctp_sk(sk)->subscribe)) {
		asoc = sctp_id2assoc(sk, 0);

		if (asoc && sctp_outq_is_empty(&asoc->outqueue)) {
			event = sctp_ulpevent_make_sender_dry_event(asoc,
					GFP_ATOMIC);
			if (!event)
				return -ENOMEM;

			sctp_ulpq_tail_event(&asoc->ulpq, event);
		}
	}

	return 0;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.