Rewrite EC_POINT_bn2point()

This is slightly asymmetric with EC_POINT_point2bn() and different from
the other "print" functions since it has to deal with the asymmetry
between BN_bin2bn() and BN_bn2bin() and allocate itself. Still, we can
make this substantially shorter than it previously was.

ok jsing

1 files changed, 15 insertions, 28 deletions

diff --git a/src/lib/libcrypto/ec/ec_print.c b/src/lib/libcrypto/ec/ec_print.c
index be5f845423..7a479a3ddc 100644
--- a/src/lib/libcrypto/ec/ec_print.c
+++ b/src/lib/libcrypto/ec/ec_print.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_print.c,v 1.18 2024/10/30 17:51:35 tb Exp $ */
+/* $OpenBSD: ec_print.c,v 1.19 2024/10/30 18:01:52 tb Exp $ */
 /* ====================================================================
  * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
  *
@@ -84,36 +84,23 @@ EC_POINT *
 EC_POINT_bn2point(const EC_GROUP *group,
     const BIGNUM *bn, EC_POINT *point, BN_CTX *ctx)
 {
+        unsigned char *buf = NULL;
         size_t buf_len = 0;
-        unsigned char *buf;
-        EC_POINT *ret;
 
+        /* Of course BN_bn2bin() is in no way symmetric to BN_bin2bn()... */
         if ((buf_len = BN_num_bytes(bn)) == 0)
-                return NULL;
-        buf = malloc(buf_len);
-        if (buf == NULL)
-                return NULL;
-
-        if (!BN_bn2bin(bn, buf)) {
-                free(buf);
-                return NULL;
-        }
-        if (point == NULL) {
-                if ((ret = EC_POINT_new(group)) == NULL) {
-                        free(buf);
-                        return NULL;
-                }
-        } else
-                ret = point;
-
-        if (!EC_POINT_oct2point(group, ret, buf, buf_len, ctx)) {
-                if (point == NULL)
-                        EC_POINT_free(ret);
-                free(buf);
-                return NULL;
-        }
-        free(buf);
-        return ret;
+                goto err;
+        if ((buf = calloc(1, buf_len)) == NULL)
+                goto err;
+        if (!BN_bn2bin(bn, buf))
+                goto err;
+        if (!ec_point_from_octets(group, buf, buf_len, &point, NULL, ctx))
+                goto err;
+
+ err:
+        freezero(buf, buf_len);
+
+        return point;
 }
 LCRYPTO_ALIAS(EC_POINT_bn2point);