[PATCH] crypto: ecrdsa - Fix incorrect use of vli_cmp

[PATCH] crypto: ecrdsa - Fix incorrect use of vli_cmp

[Vitaly Chikunov]

Correctly compare values that shall be greater-or-equal and not just
greater.

Fixes: 0d7a78643f69 ("crypto: ecrdsa - add EC-RDSA (GOST 34.10) algorithm")
Cc: <stable@vger.kernel.org>
Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
---
 crypto/ecrdsa.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/crypto/ecrdsa.c b/crypto/ecrdsa.c
index b32ffcaad9adf..f3c6b5e15e75b 100644
--- a/crypto/ecrdsa.c
+++ b/crypto/ecrdsa.c
@@ -113,15 +113,15 @@ static int ecrdsa_verify(struct akcipher_request *req)
 
 	/* Step 1: verify that 0 < r < q, 0 < s < q */
 	if (vli_is_zero(r, ndigits) ||
-	    vli_cmp(r, ctx->curve->n, ndigits) == 1 ||
+	    vli_cmp(r, ctx->curve->n, ndigits) >= 0 ||
 	    vli_is_zero(s, ndigits) ||
-	    vli_cmp(s, ctx->curve->n, ndigits) == 1)
+	    vli_cmp(s, ctx->curve->n, ndigits) >= 0)
 		return -EKEYREJECTED;
 
 	/* Step 2: calculate hash (h) of the message (passed as input) */
 	/* Step 3: calculate e = h \mod q */
 	vli_from_le64(e, digest, ndigits);
-	if (vli_cmp(e, ctx->curve->n, ndigits) == 1)
+	if (vli_cmp(e, ctx->curve->n, ndigits) >= 0)
 		vli_sub(e, e, ctx->curve->n, ndigits);
 	if (vli_is_zero(e, ndigits))
 		e[0] = 1;
@@ -137,7 +137,7 @@ static int ecrdsa_verify(struct akcipher_request *req)
 	/* Step 6: calculate point C = z_1P + z_2Q, and R = x_c \mod q */
 	ecc_point_mult_shamir(&cc, z1, &ctx->curve->g, z2, &ctx->pub_key,
 			      ctx->curve);
-	if (vli_cmp(cc.x, ctx->curve->n, ndigits) == 1)
+	if (vli_cmp(cc.x, ctx->curve->n, ndigits) >= 0)
 		vli_sub(cc.x, cc.x, ctx->curve->n, ndigits);
 
 	/* Step 7: if R == r signature is valid */
-- 
2.11.0

Re: [PATCH] crypto: ecrdsa - Fix incorrect use of vli_cmp

[Herbert Xu]

On Thu, Apr 21, 2022 at 08:25:10PM +0300, Vitaly Chikunov wrote:
> Correctly compare values that shall be greater-or-equal and not just
> greater.
> 
> Fixes: 0d7a78643f69 ("crypto: ecrdsa - add EC-RDSA (GOST 34.10) algorithm")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
> ---
>  crypto/ecrdsa.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt