Handle BN_CTX at the EC API boundary.

The EC API allows callers to optionally pass in a BN_CTX, which means that
any code needing a BN_CTX has to check if one was provided, allocate one if
not, then free it again. Rather than doing this dance throughout the EC
code, handle the BN_CTX existance at the EC API boundary. This means that
lower level implementation code can simply assume that the BN_CTX is
available.

ok tb@

1 files changed, 3 insertions, 9 deletions

diff --git a/src/lib/libcrypto/ec/ecp_mont.c b/src/lib/libcrypto/ec/ecp_mont.c
index 915cf15f72..b113855603 100644
--- a/src/lib/libcrypto/ec/ecp_mont.c
+++ b/src/lib/libcrypto/ec/ecp_mont.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ecp_mont.c,v 1.28 2023/03/27 10:25:02 tb Exp $ */
+/* $OpenBSD: ecp_mont.c,v 1.29 2023/04/11 18:58:20 jsing Exp $ */
 /*
  * Originally written by Bodo Moeller for the OpenSSL project.
  */
@@ -127,18 +127,12 @@ static int
 ec_GFp_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p, const BIGNUM *a,
     const BIGNUM *b, BN_CTX *ctx)
 {
-        BN_CTX *new_ctx = NULL;
         BN_MONT_CTX *mont = NULL;
         BIGNUM *one = NULL;
         int ret = 0;
 
         ec_GFp_mont_group_clear(group);
 
-        if (ctx == NULL) {
-                ctx = new_ctx = BN_CTX_new();
-                if (ctx == NULL)
-                        return 0;
-        }
         mont = BN_MONT_CTX_new();
         if (mont == NULL)
                 goto err;
@@ -158,14 +152,13 @@ ec_GFp_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p, const BIGNUM *a,
         one = NULL;
 
         ret = ec_GFp_simple_group_set_curve(group, p, a, b, ctx);
-
         if (!ret)
                 ec_GFp_mont_group_clear(group);
 
  err:
-        BN_CTX_free(new_ctx);
         BN_MONT_CTX_free(mont);
         BN_free(one);
+
         return ret;
 }
 
@@ -222,6 +215,7 @@ ec_GFp_mont_field_set_to_one(const EC_GROUP *group, BIGNUM *r, BN_CTX *ctx)
         }
         if (!bn_copy(r, group->mont_one))
                 return 0;
+
         return 1;
 }