2022-04-22 17:25:56

by Vitaly Chikunov

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

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: <[email protected]>
Signed-off-by: Vitaly Chikunov <[email protected]>
---
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


2022-04-29 08:47:29

by Herbert Xu

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

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: <[email protected]>
> Signed-off-by: Vitaly Chikunov <[email protected]>
> ---
> crypto/ecrdsa.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)

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