static int usb_audio_probe(struct usb_interface *intf,
			   const struct usb_device_id *usb_id)
{
	struct usb_device *dev = interface_to_usbdev(intf);
	const struct snd_usb_audio_quirk *quirk =
		(const struct snd_usb_audio_quirk *)usb_id->driver_info;
	struct snd_usb_audio *chip;
	int i, err;
	struct usb_host_interface *alts;
	int ifnum;
	u32 id;

	alts = &intf->altsetting[0];
	ifnum = get_iface_desc(alts)->bInterfaceNumber;
	id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
		    le16_to_cpu(dev->descriptor.idProduct));
	if (get_alias_id(dev, &id))
		quirk = get_alias_quirk(dev, id);
	if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
		return -ENXIO;

	err = snd_usb_apply_boot_quirk(dev, intf, quirk, id);
	if (err < 0)
		return err;

	/*
	 * found a config.  now register to ALSA
	 */

	/* check whether it's already registered */
	chip = NULL;
	mutex_lock(&register_mutex);
	for (i = 0; i < SNDRV_CARDS; i++) {
		if (usb_chip[i] && usb_chip[i]->dev == dev) {
			if (atomic_read(&usb_chip[i]->shutdown)) {
				dev_err(&dev->dev, "USB device is in the shutdown state, cannot create a card instance\n");
				err = -EIO;
				goto __error;
			}
			chip = usb_chip[i];
			atomic_inc(&chip->active); /* avoid autopm */
			break;
		}
	}
	if (! chip) {
		/* it's a fresh one.
		 * now look for an empty slot and create a new card instance
		 */
		for (i = 0; i < SNDRV_CARDS; i++)
			if (!usb_chip[i] &&
			    (vid[i] == -1 || vid[i] == USB_ID_VENDOR(id)) &&
			    (pid[i] == -1 || pid[i] == USB_ID_PRODUCT(id))) {
				if (enable[i]) {
					err = snd_usb_audio_create(intf, dev, i, quirk,
								   id, &chip);
					if (err < 0)
						goto __error;
					chip->pm_intf = intf;
					break;
				} else if (vid[i] != -1 || pid[i] != -1) {
					dev_info(&dev->dev,
						 "device (%04x:%04x) is disabled\n",
						 USB_ID_VENDOR(id),
						 USB_ID_PRODUCT(id));
					err = -ENOENT;
					goto __error;
				}
			}
		if (!chip) {
			dev_err(&dev->dev, "no available usb audio device\n");
			err = -ENODEV;
			goto __error;
		}
	}
	dev_set_drvdata(&dev->dev, chip);

	/*
	 * For devices with more than one control interface, we assume the
	 * first contains the audio controls. We might need a more specific
	 * check here in the future.
	 */
	if (!chip->ctrl_intf)
		chip->ctrl_intf = alts;

	chip->txfr_quirk = 0;
	err = 1; /* continue */
	if (quirk && quirk->ifnum != QUIRK_NO_INTERFACE) {
		/* need some special handlings */
		err = snd_usb_create_quirk(chip, intf, &usb_audio_driver, quirk);
		if (err < 0)
			goto __error;
	}

	if (err > 0) {
		/* create normal USB audio interfaces */
		err = snd_usb_create_streams(chip, ifnum);
		if (err < 0)
			goto __error;
		err = snd_usb_create_mixer(chip, ifnum, ignore_ctl_error);
		if (err < 0)
			goto __error;
	}

	/* we are allowed to call snd_card_register() many times */
	err = snd_card_register(chip->card);
	if (err < 0)
		goto __error;

	usb_chip[chip->index] = chip;
	chip->num_interfaces++;
	usb_set_intfdata(intf, chip);
	atomic_dec(&chip->active);
	mutex_unlock(&register_mutex);
	return 0;
 
  __error:
 	if (chip) {
 		if (!chip->num_interfaces)
 			snd_card_free(chip->card);
		atomic_dec(&chip->active);
 	}
 	mutex_unlock(&register_mutex);
 	return err;
}

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.