Re: [PATCH v4 15/19] crypto: cmh - add ML-KEM/ML-DSA (QSE)

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] ML-DSA implementation incorrectly rejects 0-length messages, preventing signing and verification of empty messages.
--

commit 69ecf7bfc1b6bb507d086ddc8d892b5e6791e35f
Author: Alex Ousherovitch <aousherovitch@rambus.com>

crypto: cmh - add ML-KEM/ML-DSA (QSE)

Register ML-KEM (Kyber) and ML-DSA (Dilithium) algorithms using the CMH
QSE core (core ID 0x09).

> diff --git a/drivers/crypto/cmh/cmh_pqc_mldsa.c b/drivers/crypto/cmh/cmh_pqc_mldsa.c
> new file mode 100644
> index 0000000000000..cbaba7d63b437
> --- /dev/null
> +++ b/drivers/crypto/cmh/cmh_pqc_mldsa.c
> @@ -0,0 +1,389 @@
[ ... ]
> +static int cmh_mldsa_sign(struct crypto_sig *tfm,
> +			  const void *src, unsigned int slen,
> +			  void *dst, unsigned int dlen)
> +{
[ ... ]
> +	if (ctx->key.mode != CMH_KEY_RAW)
> +		return -EINVAL;
> +	if (dlen < sig_size)
> +		return -EINVAL;
> +	if (!slen || slen > ML_DSA_MAX_MLEN)
> +		return -EINVAL;

[Severity: High]
Does this incorrectly reject valid 0-length messages?

Because this driver overrides the kernel's fallback implementation with a
higher priority (5001), system-wide empty message signing operations could
unconditionally fail with -EINVAL, violating the FIPS 204 specification.

[ ... ]
> +static int cmh_mldsa_verify(struct crypto_sig *tfm,
> +			    const void *src, unsigned int slen,
> +			    const void *digest, unsigned int dlen)
> +{
[ ... ]
> +	if (!ctx->pub_key)
> +		return -EINVAL;
> +	if (slen != sig_size)
> +		return -EINVAL;
> +	if (!dlen || dlen > ML_DSA_MAX_MLEN)
> +		return -EINVAL;

[Severity: High]
Does this also incorrectly reject valid 0-length messages for verification?

Similar to signing, this could block drop-in compatibility for userspace or
kernel components verifying an empty payload.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260825221539.255951-1-aousherovitch@rambus.com?part=15