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

	for (nbytes = crypto_hash_walk_first(req, &walk); nbytes > 0;
	     nbytes = crypto_hash_walk_done(&walk, nbytes))
		nbytes = crypto_shash_update(desc, walk.data, nbytes);

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This weakness pertains to the use of cryptographic functions that are weak, misconfigured, or outdated, which undermines the intended protection of encrypted data and communications.