Avoid recycling ASN1_STRINGs when decoding ASN.1.

Rather than recycling an existing ASN1_STRING and changing its type, free
it and allocate a replacement. This simplifies the code and potentially
avoids bugs resulting from reuse.

ok tb@

diff --git a/lib/libcrypto/asn1/tasn_dec.c b/lib/libcrypto/asn1/tasn_dec.c
index 457f526..f89d8e1 100644 (file)
--- a/lib/libcrypto/asn1/tasn_dec.c
+++ b/lib/libcrypto/asn1/tasn_dec.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tasn_dec.c,v 1.80 2022/09/03 18:52:18 jsing Exp $ */
+/* $OpenBSD: tasn_dec.c,v 1.81 2022/09/03 19:11:45 jsing Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2000.
  */
@@ -276,7 +276,7 @@ asn1_find_end(CBS *cbs, size_t length, int indefinite)
 static int
 asn1_c2i_primitive(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *it)
 {
-       ASN1_STRING *stmp;
+       ASN1_STRING *astr;
        ASN1_BOOLEAN *tbool;
        uint8_t u8val;
        int ret = 0;
@@ -361,21 +361,19 @@ asn1_c2i_primitive(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *
                        }
                }
                /* All based on ASN1_STRING and handled the same way. */
-               if (*pval == NULL) {
-                       if ((stmp = ASN1_STRING_type_new(utype)) == NULL) {
-                               ASN1error(ERR_R_MALLOC_FAILURE);
-                               goto err;
-                       }
-                       *pval = (ASN1_VALUE *)stmp;
-               } else {
-                       stmp = (ASN1_STRING *)*pval;
-                       stmp->type = utype;
-               }
-               if (!ASN1_STRING_set(stmp, CBS_data(content), CBS_len(content))) {
-                       ASN1_STRING_free(stmp);
+               if (*pval != NULL) {
+                       ASN1_STRING_free((ASN1_STRING *)*pval);
                        *pval = NULL;
+               }
+               if ((astr = ASN1_STRING_type_new(utype)) == NULL) {
+                       ASN1error(ERR_R_MALLOC_FAILURE);
+                       goto err;
+               }
+               if (!ASN1_STRING_set(astr, CBS_data(content), CBS_len(content))) {
+                       ASN1_STRING_free(astr);
                        goto err;
                }
+               *pval = (ASN1_VALUE *)astr;
                break;
        }