Sys HostIP flawed by mod_perl bug [rt.cpan.org #23577]

[xsawyerx]

https://rt.cpan.org/Ticket/Display.html?id=23577

There is a bug in the 1.99 series of mod_perl that flaws apache if you
use Sys::HostIP on Linux / Mac. This is caused by a call to "local %ENV"
in HostIP.pm. It got fixed at some point and should be ok in the latest
mod_perl 2+...

If you are using mod_perl 1.99* on *NIX with Sys::HostIP 1.3.1 beware...

See:
http://www.google.co.uk/search?q=site:apache.org+%22local+env%22+walsham&num=100&hl=en&lr=&filter=0



====================================================================

Hi Jonathan,

Thank you for the very useful Sys::HostIP.

I thought you might be interested to know there is a problem in the
latest mod_perl versions that causes a problem for Sys::HostIP. The bug
details I posted to [email protected] are below.

Within the environments I am running, commenting out local %ENV in 
_get_unix_interface_info is enough to get things working ok, although I 
realise this might not be ok for everyone.

Best Wishes

Peter Walsham



Summary
============

Calling "local %ENV" from anywhere inside a mod_perl handler will 
terminally flaw the httpd process. The httpd process will function fine
on the first request, but will die the next time it is asked to handle a
request.

Apache error.log or error_log will contain one of the following.

[notice] child pid <PID> exit signal Segmentation fault (11)
[notice] child pid <PID> exit signal Bus error (10)

Calling local %ENV seems fine on:
mod_perl 1.99_09 

Calling local %ENV creates a terminal flaw on:
mod_perl 1.99_16 
mod_perl 1.999_21 
mod_perl 2.0.2

I spotted this because I was using Sys::HostIP, which has been calling
local %ENV inside _get_unix_interface_info since version 1.1 (07 Apr 
2002).
http://search.cpan.org/src/BLUELINES/Sys-HostIP-1.1/HostIP.pm
http://search.cpan.org/src/BLUELINES/Sys-HostIP-1.3.1/HostIP.pm

Some example test files are given below.


Testing Performed On
=========================
Main tests on:
Fedora Core 3
Mac OS X 10.3.9

Results were consistent with other installs on:
Red Hat 9
Fedora Core 2 (FC2)
Fedora Core 4 (FC4)
Red Hat Enterprise Linux 3 (RHEL3)
Mac OS X 10.4.3
Windows Server 2000
Windows Server 2003
Windows XP Pro



Configuring httpd.conf
===========================

For ease of testing reduce the number of forked httpd processes in 
httpd.conf: 

<IfModule prefork.c>
StartServers         1
MinSpareServers      1
MaxSpareServers      1
MaxClients         150
MaxRequestsPerChild  0
</IfModule>




Fedora Core 3
==================

First tried with the RPMs FC3 came with:
httpd-2.0.52-3.i386.rpm
mod_perl-1.99_16-3.rpm


Then upgraded to latest mod_perl and Apache to see if the problem had 
been fixed (which it hadn't).
mod_perl 2.0.2 (VERSION 2.000002)
Apache   2.0.53
Perl     5.8.5

The process dies with:
[notice] child pid <PID> exit signal Segmentation fault (11)



FILE: Mod_Perl_ENV_Bug_Test.conf

LoadModule perl_module modules/mod_perl.so

Listen 80

<VirtualHost *:80>
  PerlOptions  +Parent
  PerlSwitches -Mlib=/home/myhome/Mod_Perl_ENV_Bug_Test
  PerlModule   Bundle::Apache2
  PerlModule   MyHandler
  <LocationMatch ^/+$>
    SetHandler          perl-script
    PerlResponseHandler MyHandler
  </LocationMatch>
</VirtualHost>



FILE: /home/myhome/Mod_Perl_ENV_Bug_Test/MyHandler.pm

package MyHandler;

use strict;
use warnings;
use Apache2::RequestRec ();
use Apache2::Const ('-compile',('OK'));
use Sys::HostIP;

sub handler($) {
    my $r = shift();
    # The error is produced by either of the following two lines
    local %ENV;
    #Sys::HostIP->ips();
    $r->content_type('text/html');
    print('Testing');
    return Apache2::Const::OK;
}

1;




Mac OS X 10.3.9
====================

mod_perl was compiled from source.

Darwin Kernel Version 7.9.0
mod_perl 2.0.0-RC4 (VERSION 1.999021) 
Apache   2.0.52
Perl     5.8.1-RC3

The process dies with:
[notice] child pid <PID> exit signal Bus error (10)



FILE: Mod_Perl_ENV_Bug_Test.conf

LoadModule perl_module modules/mod_perl.so

Listen 80

<VirtualHost *:80>
  PerlOptions  +Parent
  PerlSwitches -Mlib=/home/myhome/Mod_Perl_ENV_Bug_Test
  PerlModule   Apache2
  PerlModule   MyHandler
  <LocationMatch ^/+$>
    SetHandler          perl-script
    PerlResponseHandler MyHandler
  </LocationMatch>
</VirtualHost>



FILE: /home/myhome/Mod_Perl_ENV_Bug_Test/MyHandler.pm

package MyHandler;

use strict;
use warnings;
use Apache::RequestRec ();
use Apache::Const -compile=>qw(OK);
use Sys::HostIP;

sub handler($) {
    my $r = shift();
    # The error is produced by either of the following two lines
    local %ENV;
    #Sys::HostIP->ips();
    $r->content_type('text/html');
    print('Testing');
    return Apache::OK;
}

1;





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