Wednesday, August 19, 2009

Httpd Exited on Signal 11 - Caused by Buggy Script

Httpd Exited on Signal 11 - Caused by Buggy Script

July 31, 2005 Posted by KP

My security run output of today contains lots of error messages like:

pid 90742 (httpd), uid 80: exited on signal 11

pid 90896 (httpd), uid 80: exited on signal 11

It looks like a serious problem, then I searched the Internet immediately, here is a helpful discussion. Although there are no definite answers, the possible reasons can be summarized as:

1. Hardware problems, the most common one.

2. Vulnerable version of Apache, PHP or other Apache modules.

3. Buggy scripts.

Regarding my server

1. Hardware problems

This server has been running well for several months, unlikely to be the case.

2. Vulnerable version of Apache or its modules

Normally I can ignore this since I monitor the packages closely with portaudit. But recently Apache did have a known vulnerability. I ignored the upgrade because it shouldn’t affect my installation.

This only affects installations where Apache is used as HTTP proxy in combination with the following web servers.

3. Buggy scripts

I did install mambo yesterday and it has a very weird problem, admin login doesn’t work. There are many similar bug reports without solutions on their support forum, which is very unusual for a popular CMS, IMO. I debugged the script as I wrote in a previous post, it turned out that the login script ended at a PHP function “session_start()”, it didn’t give any error message, just like calling “die()”. Then I made a test, signal 11 error happened every time I made a login.

Now the problem is clear, I removed mambo.

Danny: 我曾經有經驗是 database 裡面的 資料有問題 導致這個現像,只要把 backup 的 database restore 就解決了,例外還有底下三個方向:

- 確認 script file 沒有 UTF-8 的 BOM or Space at the beginning and end of script files.

- 看 drupal table 裡面的 watchdog table

- 在 command line interface cli 底下 執行 php drupal/index.php

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