Bug#565951: libc6 weird memory corruption error while using custom module in apache2-mpm-prefork

[Radek Antoniuk <radek.antoniuk@gmail.com>]

Package: libc6
Version: 2.7-18
Severity: normal

I am getting a segfault or segabort &  stacktrace in apache error logs while invoking custom module by apache2-mpm-prefork with php5.
    *** glibc detected *** /usr/sbin/apache2: malloc(): memory corruption: 0x0847b468 *** 
    ======= Backtrace: ========= 
    /lib/libc.so.6[0xb7d9a845] 
    /lib/libc.so.6[0xb7d9cde2] 
    /lib/libc.so.6(__libc_malloc+0x96)[0xb7d9e586] 
    /lib/libc.so.6[0xb7d8b4ff] 
    /lib/libc.so.6(fopen+0x2c)[0xb7d8b5cc] 
    /lib/libnss_files.so.2[0xb6d9aa80] 
    /lib/libnss_files.so.2(_nss_files_getprotobyname_r+0x37)[0xb6d9b067] 
    /lib/libc.so.6(getprotobyname_r+0xa2)[0xb7e12302] 
    /lib/libc.so.6(getprotobyname+0x77)[0xb7e12197] 
    /usr/lib/php5/20060613+lfs/mrl.dll(mlSndRcv+0x1e3)[0xb60f6d93] 
    /usr/lib/php5/20060613+lfs/mrl.dll(__call_mrldll+0x556)[0xb60e4558] 

It looks like it is triggered by getprotobyname or libnss...
Also, it is not easily reproducible, i.e. it happens occasionally, 4-5 times a day on a busy server.
Any ideas?


-- System Information:
Debian Release: 5.0.3
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: i386 (i486)

Kernel: Linux 2.6.25.7 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages libc6 depends on:
ii  libgcc1                      1:4.3.2-1.1 GCC support library

libc6 recommends no packages.

Versions of packages libc6 suggests:
pn  glibc-doc                     <none>     (no description available)
pn  libc6-i686                    <none>     (no description available)
ii  locales                       2.7-18     GNU C Library: National Language (

-- debconf information:
* glibc/restart-services: openbsd-inetd cron
  glibc/restart-failed:
  glibc/upgrade: true