Re: [PATCH v4 1/3] crypto: ti - Add support for SHA224/256/384/512 in DTHEv2 driver

[T Pratham]

On 6/5/26 15:40, Herbert Xu wrote:
> On Tue, May 26, 2026 at 03:13:51PM +0530, T Pratham wrote:
>>
>> +static int dthe_hash_final(struct ahash_request *req)
>> +{
>> +	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
>> +	struct dthe_tfm_ctx *ctx = crypto_ahash_ctx(tfm);
>> +	struct dthe_hash_req_ctx *rctx = ahash_request_ctx(req);
>> +	struct dthe_data *dev_data = dthe_get_dev(ctx);
>> +	struct crypto_engine *engine = dev_data->hash_engine;
>> +
>> +	/**
>> +	 * We are always buffering data in update, except when nbytes = 0.
>> +	 * So, either we get the buffered data here (nbytes > 0) or
>> +	 * it is the case that we got zero message to begin with
>> +	 */
>> +	if (req->nbytes > 0) {
>> +		rctx->flags = DTHE_HASH_OP_FINUP;
>> +
>> +		return crypto_transfer_hash_request_to_engine(engine, req);
>> +	}
>> +
>> +	dthe_hash_write_zero_message(ctx->hash_mode, req->result);
> 
> This doesn't look right.  If I do an update of 64 bytes, and then
> call final with req->nbytes == 0, this will give me a zero-length
> hash.
> 
> Cheers,

.cra_flags sets CRYPTO_AHASH_ALG_BLOCK_ONLY and
CRYPTO_AHASH_ALG_FINAL_NONZERO flags. An update of 64 bytes will do an
update of block size and carry over at least one byte to final. We
always go into this if block when there is non-zero data coming into update.

-- 
Regards
T Pratham <t-pratham@xxxxxx>