static int snd_seq_ioctl_query_subs(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_query_subs *subs = arg;
	int result = -ENXIO;
	struct snd_seq_client *cptr = NULL;
	struct snd_seq_client_port *port = NULL;
	struct snd_seq_port_subs_info *group;
	struct list_head *p;
	int i;

	if ((cptr = snd_seq_client_use_ptr(subs->root.client)) == NULL)
		goto __end;
	if ((port = snd_seq_port_use_ptr(cptr, subs->root.port)) == NULL)
		goto __end;

	switch (subs->type) {
	case SNDRV_SEQ_QUERY_SUBS_READ:
		group = &port->c_src;
		break;
	case SNDRV_SEQ_QUERY_SUBS_WRITE:
		group = &port->c_dest;
		break;
	default:
		goto __end;
	}

	down_read(&group->list_mutex);
	/* search for the subscriber */
	subs->num_subs = group->count;
	i = 0;
	result = -ENOENT;
	list_for_each(p, &group->list_head) {
		if (i++ == subs->index) {
			/* found! */
			struct snd_seq_subscribers *s;
			if (subs->type == SNDRV_SEQ_QUERY_SUBS_READ) {
				s = list_entry(p, struct snd_seq_subscribers, src_list);
				subs->addr = s->info.dest;
			} else {
				s = list_entry(p, struct snd_seq_subscribers, dest_list);
				subs->addr = s->info.sender;
			}
			subs->flags = s->info.flags;
			subs->queue = s->info.queue;
			result = 0;
			break;
		}
	}
	up_read(&group->list_mutex);

      __end:
   	if (port)
		snd_seq_port_unlock(port);
	if (cptr)
		snd_seq_client_unlock(cptr);

	return result;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.