int shash_ahash_finup(struct ahash_request *req, struct shash_desc *desc)
{
	struct crypto_hash_walk walk;
	int nbytes;

	nbytes = crypto_hash_walk_first(req, &walk);
	if (!nbytes)
		return crypto_shash_final(desc, req->result);

	do {
		nbytes = crypto_hash_walk_last(&walk) ?
			 crypto_shash_finup(desc, walk.data, nbytes,
					    req->result) :
			 crypto_shash_update(desc, walk.data, nbytes);
		nbytes = crypto_hash_walk_done(&walk, nbytes);
	} while (nbytes > 0);

	return nbytes;
}

This weakness pertains to the use of cryptographic functions that are weak, misconfigured, or outdated, which undermines the intended protection of encrypted data and communications.