Switch ec_asn1_group2parameters() to get0_{order,cofactor}()

These are more ergonomic, result in more readable code, avoid a copy and
we no longer ignore a possible memory allocation error due to API misdesign
and bad code.

ok jsing

1 files changed, 14 insertions, 11 deletions

diff --git a/src/lib/libcrypto/ec/ec_asn1.c b/src/lib/libcrypto/ec/ec_asn1.c
index 0fe187aeb1..02609606ff 100644
--- a/src/lib/libcrypto/ec/ec_asn1.c
+++ b/src/lib/libcrypto/ec/ec_asn1.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_asn1.c,v 1.72 2024/10/14 18:17:11 tb Exp $ */
+/* $OpenBSD: ec_asn1.c,v 1.73 2024/10/15 06:35:59 tb Exp $ */
 /*
  * Written by Nils Larsch for the OpenSSL project.
  */
@@ -695,15 +695,11 @@ ec_asn1_group2parameters(const EC_GROUP *group)
         int ok = 0;
         size_t len = 0;
         ECPARAMETERS *ret = NULL;
-        BIGNUM *tmp = NULL;
+        const BIGNUM *order, *cofactor;
         unsigned char *buffer = NULL;
         const EC_POINT *point = NULL;
         point_conversion_form_t form;
 
-        if ((tmp = BN_new()) == NULL) {
-                ECerror(ERR_R_MALLOC_FAILURE);
-                goto err;
-        }
         if ((ret = ECPARAMETERS_new()) == NULL) {
                 ECerror(ERR_R_MALLOC_FAILURE);
                 goto err;
@@ -750,19 +746,27 @@ ec_asn1_group2parameters(const EC_GROUP *group)
                 ECerror(ERR_R_ASN1_LIB);
                 goto err;
         }
-        if (!EC_GROUP_get_order(group, tmp, NULL)) {
+        if ((order = EC_GROUP_get0_order(group)) == NULL) {
+                ECerror(ERR_R_EC_LIB);
+                goto err;
+        }
+        if (BN_is_zero(order)) {
                 ECerror(ERR_R_EC_LIB);
                 goto err;
         }
         ASN1_INTEGER_free(ret->order);
-        if ((ret->order = BN_to_ASN1_INTEGER(tmp, NULL)) == NULL) {
+        if ((ret->order = BN_to_ASN1_INTEGER(order, NULL)) == NULL) {
                 ECerror(ERR_R_ASN1_LIB);
                 goto err;
         }
         ASN1_INTEGER_free(ret->cofactor);
         ret->cofactor = NULL;
-        if (EC_GROUP_get_cofactor(group, tmp, NULL)) {
-                if ((ret->cofactor = BN_to_ASN1_INTEGER(tmp, NULL)) == NULL) {
+        if ((cofactor = EC_GROUP_get0_cofactor(group)) == NULL) {
+                ECerror(ERR_R_EC_LIB);
+                goto err;
+        }
+        if (!BN_is_zero(cofactor)) {
+                if ((ret->cofactor = BN_to_ASN1_INTEGER(cofactor, NULL)) == NULL) {
                         ECerror(ERR_R_ASN1_LIB);
                         goto err;
                 }
@@ -774,7 +778,6 @@ ec_asn1_group2parameters(const EC_GROUP *group)
                 ECPARAMETERS_free(ret);
                 ret = NULL;
         }
-        BN_free(tmp);
         free(buffer);
         return (ret);
 }