From 73df5c80538970ee1fbc4fe3348109bdc281e197 Mon Sep 17 00:00:00 2001
From: Aram Sargsyan <aram@isc.org>
Date: Thu, 18 Aug 2022 08:59:09 +0000
Subject: [PATCH] Fix memory leaks in DH code

When used with OpenSSL v3.0.0+, the `openssldh_compare()`,
`openssldh_paramcompare()`, and `openssldh_todns()` functions
fail to cleanup the used memory on some error paths.

Use `DST_RET` instead of `return`, when there is memory to be
released before returning from the functions.

(cherry picked from commit 73d6bbff4e1df583810126fe58eac39bb52bc0d9)
---
 lib/dns/openssldh_link.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/lib/dns/openssldh_link.c b/lib/dns/openssldh_link.c
index 30de343..2af1d30 100644
--- a/lib/dns/openssldh_link.c
+++ b/lib/dns/openssldh_link.c
@@ -68,6 +68,7 @@
 	"83655D23DCA3AD961C62F356208552BB9ED529077096966D" \
 	"670C354E4ABC9804F1746C08CA237327FFFFFFFFFFFFFFFF"
 
+#define DST_RET(a) {ret = a; goto err;}
 
 static isc_result_t openssldh_todns(const dst_key_t *key, isc_buffer_t *data);
 
@@ -186,7 +187,8 @@ openssldh_computesecret(const dst_key_t *pub, const dst_key_t *priv,
 
 static bool
 openssldh_compare(const dst_key_t *key1, const dst_key_t *key2) {
-	DH *dh1, *dh2;
+	bool ret = true;
+       DH *dh1, *dh2;
 	const BIGNUM *pub_key1 = NULL, *pub_key2 = NULL;
 	const BIGNUM *priv_key1 = NULL, *priv_key2 = NULL;
 	const BIGNUM *p1 = NULL, *g1 = NULL, *p2 = NULL, *g2 = NULL;
@@ -206,20 +208,21 @@ openssldh_compare(const dst_key_t *key1, const dst_key_t *key2) {
 
 	if (BN_cmp(p1, p2) != 0 || BN_cmp(g1, g2) != 0 ||
 	    BN_cmp(pub_key1, pub_key2) != 0)
-		return (false);
+		DST_RET(false);
 
 	if (priv_key1 != NULL || priv_key2 != NULL) {
-		if (priv_key1 == NULL || priv_key2 == NULL)
-			return (false);
-		if (BN_cmp(priv_key1, priv_key2) != 0)
-			return (false);
+		if (priv_key1 == NULL || priv_key2 == NULL ||
+                BN_cmp(priv_key1, priv_key2) != 0)
+			DST_RET(false);
 	}
-	return (true);
+err:
+	return (ret);
 }
 
 static bool
 openssldh_paramcompare(const dst_key_t *key1, const dst_key_t *key2) {
-	DH *dh1, *dh2;
+	bool ret = true;
+       DH *dh1, *dh2;
 	const BIGNUM *p1 = NULL, *g1 = NULL, *p2 = NULL, *g2 = NULL;
 
 	dh1 = key1->keydata.dh;
@@ -234,8 +237,10 @@ openssldh_paramcompare(const dst_key_t *key1, const dst_key_t *key2) {
 	DH_get0_pqg(dh2, &p2, NULL, &g2);
 
 	if (BN_cmp(p1, p2) != 0 || BN_cmp(g1, g2) != 0)
-		return (false);
-	return (true);
+		DST_RET(false);
+
+err:
+	return (ret);
 }
 
 #if OPENSSL_VERSION_NUMBER > 0x00908000L
@@ -393,7 +398,8 @@ uint16_fromregion(isc_region_t *region) {
 
 static isc_result_t
 openssldh_todns(const dst_key_t *key, isc_buffer_t *data) {
-	DH *dh;
+	isc_result_t ret = ISC_R_SUCCESS;
+    DH *dh;
 	const BIGNUM *pub_key = NULL, *p = NULL, *g = NULL;
 	isc_region_t r;
 	uint16_t dnslen, plen, glen, publen;
@@ -420,7 +426,7 @@ openssldh_todns(const dst_key_t *key, isc_buffer_t *data) {
 	publen = BN_num_bytes(pub_key);
 	dnslen = plen + glen + publen + 6;
 	if (r.length < (unsigned int) dnslen)
-		return (ISC_R_NOSPACE);
+		DST_RET(ISC_R_NOSPACE);
 
 	uint16_toregion(plen, &r);
 	if (plen == 1) {
@@ -445,7 +451,8 @@ openssldh_todns(const dst_key_t *key, isc_buffer_t *data) {
 
 	isc_buffer_add(data, dnslen);
 
-	return (ISC_R_SUCCESS);
+err:
+	return (ret);
 }
 
 static isc_result_t
@@ -659,7 +666,6 @@ openssldh_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
 	DH *dh = NULL;
 	BIGNUM *pub_key = NULL, *priv_key = NULL, *p = NULL, *g = NULL;
 	isc_mem_t *mctx;
-#define DST_RET(a) {ret = a; goto err;}
 
 	UNUSED(pub);
 	mctx = key->mctx;
-- 
2.23.0