Fix #78173: XML-RPC mutates immutable objects during encoding

With opcache.protect_memory=1 enabled, the XML-RPC extension causes a
segfault on PHP 7.2 as it is modifying the recursion counter of objects
it touches, without first checking if they are immutable or not.

This doesn't affect 7.3+

NEWS

@@ -2,6 +2,9 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? 2019, PHP 7.2.21
 
+- XMLRPC:
+  . Fixed #78173 (XML-RPC mutates immutable objects during encoding). (Asher
+    Baker)
 
 27 Jun 2019, PHP 7.2.20
 

ext/xmlrpc/xmlrpc-epi-php.c

@@ -556,7 +556,7 @@ static XMLRPC_VALUE PHP_to_XMLRPC_worker (const char* key, zval* in_val, int dep
 						XMLRPC_VECTOR_TYPE vtype;
 
 						ht = HASH_OF(&val);
-						if (ht && ht->u.v.nApplyCount > 1) {
+						if (ht && ZEND_HASH_APPLY_PROTECTION(ht) && ht->u.v.nApplyCount > 1) {
 							zend_throw_error(NULL, "XML-RPC doesn't support circular references");
 							return NULL;
 						}
@@ -570,7 +570,7 @@ static XMLRPC_VALUE PHP_to_XMLRPC_worker (const char* key, zval* in_val, int dep
 						ZEND_HASH_FOREACH_KEY_VAL(Z_ARRVAL(val_arr), num_index, my_key, pIter) {
 							ZVAL_DEREF(pIter);
 							ht = HASH_OF(pIter);
-							if (ht) {
+							if (ht && ZEND_HASH_APPLY_PROTECTION(ht)) {
 								ht->u.v.nApplyCount++;
 							}
 							if (my_key == NULL) {
@@ -587,7 +587,7 @@ static XMLRPC_VALUE PHP_to_XMLRPC_worker (const char* key, zval* in_val, int dep
 							} else {
 								XMLRPC_AddValueToVector(xReturn, PHP_to_XMLRPC_worker(ZSTR_VAL(my_key), pIter, depth++));
 							}
-							if (ht) {
+							if (ht && ZEND_HASH_APPLY_PROTECTION(ht)) {
 								ht->u.v.nApplyCount--;
 							}
 						} ZEND_HASH_FOREACH_END();