From: Vitaly Chikunov <vt@altlinux.org>
Date: Fri, 22 Apr 2022 00:02:36 +0000 (+0300)
Subject: gost_ec_sign: Fix sig verify step 1 range checks
X-Git-Tag: v3.0.2~12
X-Git-Url: http://www.wagner.pp.ru/gitweb/?p=openssl-gost%2Fengine.git;a=commitdiff_plain;h=021a2b61b5d904caaf4ceb26ff3163f1f0e4219f

gost_ec_sign: Fix sig verify step 1 range checks

Ensure 0 < r < q, 0 < s < q. (34.10-2021 6.2).

Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
---

diff --git a/gost_ec_sign.c b/gost_ec_sign.c
index 47996e1..a825dba 100644
--- a/gost_ec_sign.c
+++ b/gost_ec_sign.c
@@ -365,10 +365,10 @@ int gost_ec_verify(const unsigned char *dgst, int dgst_len,
     ECDSA_SIG_get0(sig, &sig_r, &sig_s);
 
     if (BN_is_zero(sig_s) || BN_is_zero(sig_r) ||
-        (BN_cmp(sig_s, order) >= 1) || (BN_cmp(sig_r, order) >= 1)) {
+        BN_is_negative(sig_s) || BN_is_negative(sig_r) ||
+        BN_ucmp(sig_s, order) >= 0 || BN_ucmp(sig_r, order) >= 0) {
         GOSTerr(GOST_F_GOST_EC_VERIFY, GOST_R_SIGNATURE_PARTS_GREATER_THAN_Q);
         goto err;
-
     }
 
     OPENSSL_assert(dgst_len == 32 || dgst_len == 64);