PoC for memory leak in the PHP LUA extension

$ cat /etc/issue
Ubuntu 16.04.1 LTS \n \l

$ php -v
PHP 7.0.13-0ubuntu0.16.04.1 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.13-0ubuntu0.16.04.1, Copyright (c) 1999-2016, by Zend Technologies

$ dpkg -s liblua5.2-dev | grep Version
Version: 5.2.4-1ubuntu1

$ php -i | grep '^lua '
lua support => enabled
lua extension version => 2.0.2
lua release => Lua 5.2.4
lua copyright => Lua 5.2.4  Copyright (C) 1994-2015 Lua.org, PUC-Rio
lua authors => R. Ierusalimschy, L. H. de Figueiredo, W. Celes

$ php test-assign.php
Mem at start of test (real): 362920 (2097152)
Mem at start of loop (real): 362952 (2097152)
Mem at end of loop (real): 363712 (2097152)
Mem at start of loop (real): 363712 (2097152)
Mem at end of loop (real): 364032 (2097152)
(...)
Mem at start of loop (real): 719296 (2097152)
Mem at end of loop (real): 719616 (2097152)
Mem at start of loop (real): 719616 (2097152)
Mem at end of loop (real): 719936 (2097152)
Mem at end of test (real): 719888 (2097152)

$ php test-registerCallback.php
Mem at start of test (real): 363080 (2097152)
Mem at start of loop (real): 363112 (2097152)
Mem at end of loop (real): 363872 (2097152)
Mem at start of loop (real): 363872 (2097152)
Mem at end of loop (real): 364192 (2097152)
(...)
Mem at start of loop (real): 719456 (2097152)
Mem at end of loop (real): 719776 (2097152)
Mem at start of loop (real): 719776 (2097152)
Mem at end of loop (real): 720096 (2097152)
Mem at end of test (real): 720048 (2097152)