From: Kent Sibilev <ksibilev@...>
Date: 2005-01-26T08:34:58+09:00
Subject: Re: Potential DoS in cgi.rb with apache & mod_fastcgi

I also noticed that this happens only on FreeBSD. I've never seen this 
problem since we moved to Linux.

Cheers,
Kent.

On Jan 25, 2005, at 6:20 PM, Eric Hodel wrote:

> On 25 Jan 2005, at 14:30, Xavier wrote:
>
>> Hi Group,
>>
>> I am getting many errors like the following in my apache logs:
>>
>> /usr/lib/ruby/1.8/cgi.rb:725: [BUG] rb_sys_fail() - errno == 0
>> ruby 1.8.2 (2004-12-25) [i686-linux]
>>
>> This error occurs whenever the client breaks the connection.
>> The fastcgi process logs the error and exits with an untrapped signal 
>> 6
>> error message.
>
> Attach a debugger, and you will see what fcgi.so is doing wrong (errno 
> is not set properly).
>
>> This can lead to a DoS because mod_fastcgi will stop spawning fcgi's
>> whenever processes have failed to keep running for at least 30 
>> seconds.
>>
>> How could I either prevent cgi.rb from breaking or trap and recover 
>> from
>> the signal 6?
>
> You don't.  This is Ruby saying "I don't know what's wrong, so I'm 
> freaking out and dying here and now."
>
> I sent a patch to moonwolf some time ago, but he has not responded...
>
> It turned out that patch is wrong, but I haven't had time to write the 
> correct patch.  On line 158 of fcgi.c (0.8.5) err needs to be copied 
> to errno so rb_sys_fail works correctly.
>
> -- 
> Eric Hodel - drbrain@segment7.net - http://segment7.net
> FEC2 57F1 D465 EB15 5D6E  7C11 332A 551C 796C 9F04