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Date: Thu, 21 Mar 2024 19:19:43 +0200
Message-Id: <CZZLMBXQ5DWK.3GZSP0HDMMUY7@kernel.org>
To: "Stefan Berger" <stefanb@linux.ibm.com>, <keyrings@vger.kernel.org>,
 <linux-crypto@vger.kernel.org>, <herbert@gondor.apana.org.au>,
 <davem@davemloft.net>
Cc: <linux-kernel@vger.kernel.org>, <saulo.alessandre@tse.jus.br>,
 <lukas@wunner.de>, <bbhushan2@marvell.com>
Subject: Re: [PATCH v7 10/13] crypto: ecdsa - Rename keylen to bufsize where
 necessary
From: "Jarkko Sakkinen" <jarkko@kernel.org>
References: <20240320114725.1644921-1-stefanb@linux.ibm.com>
 <20240320114725.1644921-11-stefanb@linux.ibm.com>
In-Reply-To: <20240320114725.1644921-11-stefanb@linux.ibm.com>

On Wed Mar 20, 2024 at 1:47 PM EET, Stefan Berger wrote:
> In cases where 'keylen' was referring to the size of the buffer used by
> a curve's digits, it does not reflect the purpose of the variable anymore
> once NIST P521 is used. What it refers to then is the size of the buffer,
> which may be a few bytes larger than the size a coordinate of a key.
> Therefore, rename keylen to bufsize where appropriate.
>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> Tested-by: Lukas Wunner <lukas@wunner.de>
> ---
>  crypto/ecdsa.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
> index 4daefb40c37a..4e847b59622a 100644
> --- a/crypto/ecdsa.c
> +++ b/crypto/ecdsa.c
> @@ -35,8 +35,8 @@ struct ecdsa_signature_ctx {
>  static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned cha=
r tag,
>  				  const void *value, size_t vlen, unsigned int ndigits)
>  {
> -	size_t keylen =3D ndigits * sizeof(u64);
> -	ssize_t diff =3D vlen - keylen;
> +	size_t bufsize =3D ndigits * sizeof(u64);
> +	ssize_t diff =3D vlen - bufsize;
>  	const char *d =3D value;
>  	u8 rs[ECC_MAX_BYTES];
> =20
> @@ -58,7 +58,7 @@ static int ecdsa_get_signature_rs(u64 *dest, size_t hdr=
len, unsigned char tag,
>  		if (diff)
>  			return -EINVAL;
>  	}
> -	if (-diff >=3D keylen)
> +	if (-diff >=3D bufsize)
>  		return -EINVAL;
> =20
>  	if (diff) {
> @@ -138,7 +138,7 @@ static int ecdsa_verify(struct akcipher_request *req)
>  {
>  	struct crypto_akcipher *tfm =3D crypto_akcipher_reqtfm(req);
>  	struct ecc_ctx *ctx =3D akcipher_tfm_ctx(tfm);
> -	size_t keylen =3D ctx->curve->g.ndigits * sizeof(u64);
> +	size_t bufsize =3D ctx->curve->g.ndigits * sizeof(u64);
>  	struct ecdsa_signature_ctx sig_ctx =3D {
>  		.curve =3D ctx->curve,
>  	};
> @@ -165,14 +165,14 @@ static int ecdsa_verify(struct akcipher_request *re=
q)
>  		goto error;
> =20
>  	/* if the hash is shorter then we will add leading zeros to fit to ndig=
its */
> -	diff =3D keylen - req->dst_len;
> +	diff =3D bufsize - req->dst_len;
>  	if (diff >=3D 0) {
>  		if (diff)
>  			memset(rawhash, 0, diff);
>  		memcpy(&rawhash[diff], buffer + req->src_len, req->dst_len);
>  	} else if (diff < 0) {
>  		/* given hash is longer, we take the left-most bytes */
> -		memcpy(&rawhash, buffer + req->src_len, keylen);
> +		memcpy(&rawhash, buffer + req->src_len, bufsize);
>  	}
> =20
>  	ecc_swap_digits((u64 *)rawhash, hash, ctx->curve->g.ndigits);


Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko