xml_parse_into_struct segmentation fault

How it was found

https://bugs.php.net/bug.php?id=72099

Invalid memory access while parsing XML input using xml_parse_into_struct, parser->level wasn't being checked and then used as an offset parser->ltags[parser->level-1].

Reported to developers on 2016-04-25, fixed 2016-04-25 and released at 2016-04-28, affected PHP 5.5 , 5.6 and 7.

http://php.net/ChangeLog-5.php#5.5.35 http://php.net/ChangeLog-5.php#5.6.21 http://php.net/ChangeLog-7.php#7.0.6