Replace EVP_KEY_assign_GOST() calls with EVP_PKEY_set_type()

Calling EVP_KEY_assign_GOST(pkey, NULL) has the same effect as calling
EVP_PKEY_set_type(pkey, EVP_PKEY_GOSTR01). The only difference is that
the latter form allows for error checking while the former won't let
you do that. Add comments explaining what we're actually doing: freeing
and zeroing the pkey->pkey union.

ok jsing

diff --git a/lib/libcrypto/gost/gostr341001_ameth.c b/lib/libcrypto/gost/gostr341001_ameth.c
index 9098797..fc3bce4 100644 (file)
--- a/lib/libcrypto/gost/gostr341001_ameth.c
+++ b/lib/libcrypto/gost/gostr341001_ameth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: gostr341001_ameth.c,v 1.21 2023/12/28 21:49:07 tb Exp $ */
+/* $OpenBSD: gostr341001_ameth.c,v 1.22 2023/12/28 21:53:09 tb Exp $ */
 /*
  * Copyright (c) 2014 Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
  * Copyright (c) 2005-2006 Cryptocom LTD
@@ -207,7 +207,9 @@ pub_decode_gost01(EVP_PKEY *pk, X509_PUBKEY *pub)
        if (X509_PUBKEY_get0_param(&palgobj, &pubkey_buf, &pub_len, &palg, pub)
            == 0)
                return 0;
-       (void)EVP_PKEY_assign_GOST(pk, NULL);
+       /* Called for the side effect of freeing pk->pkey. */
+       if (!EVP_PKEY_set_type(pk, EVP_PKEY_GOSTR01))
+               return 0;
        X509_ALGOR_get0(NULL, &ptype, (const void **)&pval, palg);
        if (ptype != V_ASN1_SEQUENCE) {
                GOSTerror(GOST_R_BAD_KEY_PARAMETERS_FORMAT);
@@ -420,7 +422,9 @@ priv_decode_gost01(EVP_PKEY *pk, const PKCS8_PRIV_KEY_INFO *p8inf)
                GOSTerror(GOST_R_BAD_KEY_PARAMETERS_FORMAT);
                return 0;
        }
-       (void)EVP_PKEY_assign_GOST(pk, NULL);
+       /* Called for the side effect of freeing pk->pkey. */
+       if (!EVP_PKEY_set_type(pk, EVP_PKEY_GOSTR01))
+               return 0;
        X509_ALGOR_get0(NULL, &ptype, (const void **)&pval, palg);
        if (ptype != V_ASN1_SEQUENCE) {
                GOSTerror(GOST_R_BAD_KEY_PARAMETERS_FORMAT);