static int __must_check ffs_do_single_os_desc(char *data, unsigned len,
					      enum ffs_os_desc_type type,
					      u16 feature_count,
					      ffs_os_desc_callback entity,
					      void *priv,
					      struct usb_os_desc_header *h)
{
	int ret;
	const unsigned _len = len;

	ENTER();

	/* loop over all ext compat/ext prop descriptors */
	while (feature_count--) {
		ret = entity(type, h, data, len, priv);
		if (unlikely(ret < 0)) {
			pr_debug("bad OS descriptor, type: %d\n", type);
			return ret;
		}
		data += ret;
		len -= ret;
	}
	return _len - len;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.