int snd_seq_device_new(struct snd_card *card, int device, const char *id,
		       int argsize, struct snd_seq_device **result)
{
	struct snd_seq_device *dev;
	int err;
	static struct snd_device_ops dops = {
		.dev_free = snd_seq_device_dev_free,
		.dev_register = snd_seq_device_dev_register,
		.dev_disconnect = snd_seq_device_dev_disconnect,
	};

	if (result)
		*result = NULL;

	if (snd_BUG_ON(!id))
		return -EINVAL;

	dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
	if (!dev)
		return -ENOMEM;

	/* set up device info */
	dev->card = card;
	dev->device = device;
	dev->id = id;
	dev->argsize = argsize;

	device_initialize(&dev->dev);
	dev->dev.parent = &card->card_dev;
	dev->dev.bus = &snd_seq_bus_type;
	dev->dev.release = snd_seq_dev_release;
	dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device);

	/* add this device to the list */
	err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops);
	if (err < 0) {
		put_device(&dev->dev);
		return err;
	}
	
	if (result)
		*result = dev;

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.