Simplify DH_check_params a bit.

It makes no sense to allocate an entire BN_CTX if we only use it to
get a single BIGNUM, from which we subtract 1 to compare it to g.
We can just use a plain BIGNUM and delete a bunch of lines.

ok inoguchi jsing

1 files changed, 4 insertions, 12 deletions

diff --git a/src/lib/libcrypto/dh/dh_check.c b/src/lib/libcrypto/dh/dh_check.c
index 7b9fcbdf5a..a3d2c98c34 100644
--- a/src/lib/libcrypto/dh/dh_check.c
+++ b/src/lib/libcrypto/dh/dh_check.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dh_check.c,v 1.21 2021/11/29 20:02:14 tb Exp $ */
+/* $OpenBSD: dh_check.c,v 1.22 2021/12/05 13:45:26 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -68,18 +68,11 @@
 int
 DH_check_params(const DH *dh, int *flags)
 {
-        BN_CTX *ctx = NULL;
-        BIGNUM *max_g;
+        BIGNUM *max_g = NULL;
         int ok = 0;
 
         *flags = 0;
 
-        if ((ctx = BN_CTX_new()) == NULL)
-                goto err;
-        BN_CTX_start(ctx);
-        if ((max_g = BN_CTX_get(ctx)) == NULL)
-                goto err;
-
         if (!BN_is_odd(dh->p))
                 *flags |= DH_CHECK_P_NOT_PRIME;
 
@@ -90,7 +83,7 @@ DH_check_params(const DH *dh, int *flags)
         if (BN_cmp(dh->g, BN_value_one()) <= 0)
                 *flags |= DH_NOT_SUITABLE_GENERATOR;
         /* max_g = p - 1 */
-        if (BN_copy(max_g, dh->p) == NULL)
+        if ((max_g = BN_dup(dh->p)) == NULL)
                 goto err;
         if (!BN_sub_word(max_g, 1))
                 goto err;
@@ -101,8 +94,7 @@ DH_check_params(const DH *dh, int *flags)
         ok = 1;
 
  err:
-        BN_CTX_end(ctx);
-        BN_CTX_free(ctx);
+        BN_free(max_g);
 
         return ok;
 }