Rewrite X509v3_add_ext()

This is another brilliancy straight out of muppet labs. Overeager and
misguided sprinkling of NULL checks, going through the trademark poor
code review, made this have semantics not matching what almost every
other function with this signature would be doing in OpenSSL land.

This is a long standing mistake we can't fix without introducing
portability traps, but at least annotate it. Simplify the elaborate
dance steps and make this resemble actual code.

ok jsing

1 files changed, 23 insertions, 24 deletions

diff --git a/lib/libcrypto/x509/x509_v3.c b/lib/libcrypto/x509/x509_v3.c
index cca74e734a0..b0a30db2e8d 100644
--- a/lib/libcrypto/x509/x509_v3.c
+++ b/lib/libcrypto/x509/x509_v3.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: x509_v3.c,v 1.33 2024/07/12 08:46:45 tb Exp $ */
+/* $OpenBSD: x509_v3.c,v 1.34 2024/07/12 08:58:59 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -145,42 +145,41 @@ LCRYPTO_ALIAS(X509v3_delete_ext);
 STACK_OF(X509_EXTENSION) *
 X509v3_add_ext(STACK_OF(X509_EXTENSION) **x, X509_EXTENSION *ext, int loc)
 {
-	X509_EXTENSION *new_ext = NULL;
-	int n;
 	STACK_OF(X509_EXTENSION) *sk = NULL;
+	X509_EXTENSION *new_ext = NULL;
 
+	/*
+	 * XXX - Nonsense from the poorly reviewed OpenSSL c755c5fd8ba (2005).
+	 * This check should have been joined with the next check, i.e., if no
+	 * stack was passed in, a new one should be created and returned.
+	 */
 	if (x == NULL) {
 		X509error(ERR_R_PASSED_NULL_PARAMETER);
-		goto err2;
+		goto err;
 	}
 
-	if (*x == NULL) {
-		if ((sk = sk_X509_EXTENSION_new_null()) == NULL)
-			goto err;
-	} else
-		sk= *x;
-
-	n = sk_X509_EXTENSION_num(sk);
-	if (loc > n)
-		loc = n;
-	else if (loc < 0)
-		loc = n;
+	if ((sk = *x) == NULL)
+		sk = sk_X509_EXTENSION_new_null();
+	if (sk == NULL) {
+		X509error(ERR_R_MALLOC_FAILURE);
+		goto err;
+	}
 
 	if ((new_ext = X509_EXTENSION_dup(ext)) == NULL)
-		goto err2;
+		goto err;
 	if (!sk_X509_EXTENSION_insert(sk, new_ext, loc))
 		goto err;
-	if (*x == NULL)
-		*x = sk;
+	new_ext = NULL;
+
+	*x = sk;
+
 	return sk;
 
  err:
-	X509error(ERR_R_MALLOC_FAILURE);
- err2:
-	if (new_ext != NULL)
-		X509_EXTENSION_free(new_ext);
-	if (sk != NULL && x != NULL && sk != *x)
-		sk_X509_EXTENSION_free(sk);
+	X509_EXTENSION_free(new_ext);
+	if (x != NULL && sk != *x)
+		sk_X509_EXTENSION_pop_free(sk, X509_EXTENSION_free);
+
 	return NULL;
 }
 LCRYPTO_ALIAS(X509v3_add_ext);