# virtual(), an easy way to put Apache server in spirals down.

- Thread: https://externals.io/message/10247
- Original archive: https://news-web.php.net/php.internals/10247
- Started by NTPT on 2004-06-02T13:48:32+00:00
- Messages: 3
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## #10248 — Paul G — 2004-06-02T13:47:46+00:00

URL: https://externals.io/message/10247#10248 · In reply to: #10247

do you have a maximum mem restriction in your php.ini?

paul

----- Original Message ----- 
From: "NTPT" <ntpt@centrum.cz>
To: <internals@lists.php.net>
Sent: Wednesday, June 02, 2004 9:48 AM
Subject: [PHP-DEV] virtual(), an easy way to put Apache server in spirals
down.


Hi.

I think following things may be a security risk in mod_php, maybe allowing a
DoS attak if your server users can use  php engine for your www pages.


If you make a file  foo.php what contains  function  virtual(), pointing to
itself, ie virtual(foo.php)
at least in php 4.3.2  an infinite lop occure, that eat up all the memory
and  swap, eat all the  resouces and script is terminated with :

"failed to open stream: Limit of open files reached  "

and

Fatal error: Allowed memory size of 67108864 bytes exhausted at (null):0
(tried to allocate 4260 bytes) in Unknown on line 0


I suggest to add  a check for maximum recursion level in virtual() if
possible and   an appropriate directive into the php.ini file that can set
this recursion level.


Regards, NTPT

PS: please execuse my bad english

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## #10247 — NTPT — 2004-06-02T13:48:32+00:00

URL: https://externals.io/message/10247#10247

Hi.

I think following things may be a security risk in mod_php, maybe allowing a DoS attak if your server users can use  php engine for your www pages.

 
If you make a file  foo.php what contains  function  virtual(), pointing to itself, ie virtual(foo.php)
at least in php 4.3.2  an infinite lop occure, that eat up all the memory and  swap, eat all the  resouces and script is terminated with :

"failed to open stream: Limit of open files reached  "

and 

Fatal error: Allowed memory size of 67108864 bytes exhausted at (null):0 (tried to allocate 4260 bytes) in Unknown on line 0
  

I suggest to add  a check for maximum recursion level in virtual() if possible and   an appropriate directive into the php.ini file that can set this recursion level.


Regards, NTPT 

PS: please execuse my bad english

---

## #10254 — NTPT — 2004-06-02T21:30:48+00:00

URL: https://externals.io/message/10247#10254 · In reply to: #10248

I have  max execution time set to 180 and mem limit to 64 mb , there is a
3*128mb physical ram total and about 1G swap space available .

Lowering the mem limit helps a bit (take longer time and more requests
needed ), but if you do more requests  (5 - 10 at
almost same time , ie click  10* reload ), situation is the same, server
start swapping and stop almost all response, until httpd processes  are
killed by the kernel because exceeded memory limits  .....


----- Original Message ----- 
From: "Paul G" <paul@rusko.us>
To: <internals@lists.php.net>
Sent: Wednesday, June 02, 2004 3:47 PM
Subject: Re: [PHP-DEV] virtual(), an easy way to put Apache server in
spirals down.


> do you have a maximum mem restriction in your php.ini?
>
> paul
>
> ----- Original Message ----- 
> From: "NTPT" <ntpt@centrum.cz>
> To: <internals@lists.php.net>
> Sent: Wednesday, June 02, 2004 9:48 AM
> Subject: [PHP-DEV] virtual(), an easy way to put Apache server in spirals
> down.
>
>
> Hi.
>
> I think following things may be a security risk in mod_php, maybe allowing
a
> DoS attak if your server users can use  php engine for your www pages.
>
>
> If you make a file  foo.php what contains  function  virtual(), pointing
to
> itself, ie virtual(foo.php)
> at least in php 4.3.2  an infinite lop occure, that eat up all the memory
> and  swap, eat all the  resouces and script is terminated with :
>
> "failed to open stream: Limit of open files reached  "
>
> and
>
> Fatal error: Allowed memory size of 67108864 bytes exhausted at (null):0
> (tried to allocate 4260 bytes) in Unknown on line 0
>
>
> I suggest to add  a check for maximum recursion level in virtual() if
> possible and   an appropriate directive into the php.ini file that can set
> this recursion level.
>
>
> Regards, NTPT
>
> PS: please execuse my bad english