Fix bug #68567 (JSON_PARTIAL_OUTPUT_ON_ERROR can result in JSON with null key)

NEWS

@@ -22,6 +22,10 @@ PHP                                                                        NEWS
 - Fileinfo:
   . Upgrade bundled libmagic to 5.31. (Anatol)
 
+- JSON:
+  . Fixed bug #68567 (JSON_PARTIAL_OUTPUT_ON_ERROR can result in JSON with null
+    key). (Jakub Zelenka)
+
 - Opcache:
   . Fixed bug #75370 (Webserver hangs on valid PHP text). (Laruence)
   . Fixed bug #75357 (segfault loading WordPress wp-admin). (Laruence)

ext/json/json_encoder.c

@@ -189,8 +189,13 @@ static int php_json_encode_array(smart_str *buf, zval *val, int options, php_jso
 					php_json_pretty_print_char(buf, options, '\n');
 					php_json_pretty_print_indent(buf, options, encoder);
 
-					php_json_escape_string(buf, ZSTR_VAL(key), ZSTR_LEN(key),
-							options & ~PHP_JSON_NUMERIC_CHECK, encoder);
+					if (php_json_escape_string(buf, ZSTR_VAL(key), ZSTR_LEN(key),
+								options & ~PHP_JSON_NUMERIC_CHECK, encoder) == FAILURE &&
+							(options & PHP_JSON_PARTIAL_OUTPUT_ON_ERROR) &&
+							buf->s) {
+						ZSTR_LEN(buf->s) -= 4;
+						smart_str_appendl(buf, "\"\"", 2);
+					}
 				} else {
 					if (need_comma) {
 						smart_str_appendc(buf, ',');

ext/json/tests/bug68567.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Bug #68567 JSON_PARTIAL_OUTPUT_ON_ERROR can result in JSON with null key
+--SKIPIF--
+<?php if (!extension_loaded("json")) print "skip"; ?>
+--FILE--
+<?php
+
+var_dump(json_encode(array("\x80" => 1), JSON_PARTIAL_OUTPUT_ON_ERROR));
+
+?>
+===DONE===
+--EXPECTF--
+string(6) "{"":1}"
+===DONE===