Description:
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In current implementation, setlocale does not handle non-primitive types correctly.
if the second argument to setlocal is not a primitive type, zval_try_get_string returns NULL and crashes try_setlocale_str during strcmp.

potentially, it can be used to DOS a remote server.

This bug is found by Yihui Zeng, Jayakrishna Menon, Steven Wirsz, and Gokul Krishna P from Arizona State University for class CSE598 Applied Vulnerability Research.

a poc is attached

Test script:
---------------
<?php
$a = xml_parser_create( );
setlocale(0, $a);
?>