Free up ADB and CHOICE if already initialised.

CVE-2015-0287
Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NEmilia Käsper <emilia@openssl.org>

crypto/asn1/tasn_dec.c

@@ -303,9 +303,16 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
     case ASN1_ITYPE_CHOICE:
         if (asn1_cb && !asn1_cb(ASN1_OP_D2I_PRE, pval, it, NULL))
             goto auxerr;
-
-        /* Allocate structure */
-        if (!*pval && !ASN1_item_ex_new(pval, it)) {
+        if (*pval) {
+            /* Free up and zero CHOICE value if initialised */
+            i = asn1_get_choice_selector(pval, it);
+            if ((i >= 0) && (i < it->tcount)) {
+                tt = it->templates + i;
+                pchptr = asn1_get_field_ptr(pval, tt);
+                ASN1_template_free(pchptr, tt);
+                asn1_set_choice_selector(pval, -1, it);
+            }
+        } else if (!ASN1_item_ex_new(pval, it)) {
             ASN1err(ASN1_F_ASN1_ITEM_EX_D2I, ERR_R_NESTED_ASN1_ERROR);
             goto err;
         }
@@ -385,6 +392,17 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
         if (asn1_cb && !asn1_cb(ASN1_OP_D2I_PRE, pval, it, NULL))
             goto auxerr;
 
+        /* Free up and zero any ADB found */
+        for (i = 0, tt = it->templates; i < it->tcount; i++, tt++) {
+            if (tt->flags & ASN1_TFLG_ADB_MASK) {
+                const ASN1_TEMPLATE *seqtt;
+                ASN1_VALUE **pseqval;
+                seqtt = asn1_do_adb(pval, tt, 1);
+                pseqval = asn1_get_field_ptr(pval, seqtt);
+                ASN1_template_free(pseqval, seqtt);
+            }
+        }
+
         /* Get each field entry */
         for (i = 0, tt = it->templates; i < it->tcount; i++, tt++) {
             const ASN1_TEMPLATE *seqtt;