static int __ffs_data_do_entity(enum ffs_entity_type type,
				u8 *valuep, struct usb_descriptor_header *desc,
				void *priv)
{
	struct ffs_desc_helper *helper = priv;
	struct usb_endpoint_descriptor *d;

	ENTER();

	switch (type) {
	case FFS_DESCRIPTOR:
		break;

	case FFS_INTERFACE:
		/*
		 * Interfaces are indexed from zero so if we
		 * encountered interface "n" then there are at least
		 * "n+1" interfaces.
		 */
		if (*valuep >= helper->interfaces_count)
			helper->interfaces_count = *valuep + 1;
		break;

	case FFS_STRING:
		/*
		 * Strings are indexed from 1 (0 is magic ;) reserved
		 * for languages list or some such)
		 */
		if (*valuep > helper->ffs->strings_count)
			helper->ffs->strings_count = *valuep;
		break;

	case FFS_ENDPOINT:
		d = (void *)desc;
		helper->eps_count++;
		if (helper->eps_count >= 15)
			return -EINVAL;
		/* Check if descriptors for any speed were already parsed */
		if (!helper->ffs->eps_count && !helper->ffs->interfaces_count)
			helper->ffs->eps_addrmap[helper->eps_count] =
				d->bEndpointAddress;
		else if (helper->ffs->eps_addrmap[helper->eps_count] !=
				d->bEndpointAddress)
			return -EINVAL;
		break;
	}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.