static int deliver_to_subscribers(struct snd_seq_client *client,
				  struct snd_seq_event *event,
				  int atomic, int hop)
{
	struct snd_seq_subscribers *subs;
	int err, result = 0, num_ev = 0;
	struct snd_seq_event event_saved;
	struct snd_seq_client_port *src_port;
	struct snd_seq_port_subs_info *grp;

	src_port = snd_seq_port_use_ptr(client, event->source.port);
	if (src_port == NULL)
		return -EINVAL; /* invalid source port */
	/* save original event record */
	event_saved = *event;
	grp = &src_port->c_src;
	
	/* lock list */
	if (atomic)
		read_lock(&grp->list_lock);
	else
		down_read(&grp->list_mutex);
	list_for_each_entry(subs, &grp->list_head, src_list) {
		/* both ports ready? */
		if (atomic_read(&subs->ref_count) != 2)
			continue;
		event->dest = subs->info.dest;
		if (subs->info.flags & SNDRV_SEQ_PORT_SUBS_TIMESTAMP)
			/* convert time according to flag with subscription */
			update_timestamp_of_queue(event, subs->info.queue,
						  subs->info.flags & SNDRV_SEQ_PORT_SUBS_TIME_REAL);
		err = snd_seq_deliver_single_event(client, event,
						   0, atomic, hop);
		if (err < 0) {
			/* save first error that occurs and continue */
			if (!result)
				result = err;
			continue;
		}
		num_ev++;
		/* restore original event record */
		*event = event_saved;
	}
	if (atomic)
		read_unlock(&grp->list_lock);
	else
		up_read(&grp->list_mutex);
	*event = event_saved; /* restore */
	snd_seq_port_unlock(src_port);
	return (result < 0) ? result : num_ev;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.