 struct snd_seq_client_port *snd_seq_create_port(struct snd_seq_client *client,
 						int port)
 {
	unsigned long flags;
	struct snd_seq_client_port *new_port, *p;
	int num = -1;
	
	/* sanity check */
	if (snd_BUG_ON(!client))
		return NULL;

	if (client->num_ports >= SNDRV_SEQ_MAX_PORTS) {
		pr_warn("ALSA: seq: too many ports for client %d\n", client->number);
		return NULL;
	}

	/* create a new port */
	new_port = kzalloc(sizeof(*new_port), GFP_KERNEL);
	if (!new_port)
		return NULL;	/* failure, out of memory */
	/* init port data */
	new_port->addr.client = client->number;
	new_port->addr.port = -1;
	new_port->owner = THIS_MODULE;
	sprintf(new_port->name, "port-%d", num);
 	snd_use_lock_init(&new_port->use_lock);
 	port_subs_info_init(&new_port->c_src);
 	port_subs_info_init(&new_port->c_dest);
 
 	num = port >= 0 ? port : 0;
 	mutex_lock(&client->ports_mutex);
	write_lock_irqsave(&client->ports_lock, flags);
	list_for_each_entry(p, &client->ports_list_head, list) {
		if (p->addr.port > num)
			break;
		if (port < 0) /* auto-probe mode */
			num = p->addr.port + 1;
	}
	/* insert the new port */
 	list_add_tail(&new_port->list, &p->list);
 	client->num_ports++;
 	new_port->addr.port = num;	/* store the port number in the port */
 	write_unlock_irqrestore(&client->ports_lock, flags);
 	mutex_unlock(&client->ports_mutex);
	sprintf(new_port->name, "port-%d", num);
 
 	return new_port;
 }

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.