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Core dumps being created

Started by greyknight17, May 26, 2008, 05:56:04 PM

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Captain Kaos

Ill ring them and ask  , Ill get back to you
Captain Kaos
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Only stupid people that don't ask them !!!!

greyknight17

My host is not doing much here. I just want to get to the bottom of this and see what's causing it before I move over to another host.

Captain Kaos

Hey Guys
My ISP was not happy to help, I did not expect that from them, so one thing i did try and was to go back to PHP v5 and still i have not had any more core files, both forums i run are now preforming perfect.
soryy cant give you any more info than that.
I do know only change on server was made , they installed some SUPHP software ????
as the Core files did not have owner ship this allocated them to the hostee's account
so then they would stop being created when there limit was exceeded.

hope you can make sence of that
Captain Kaos
© 2009 Kaos.Inc
Powered by Mac OSX
-----------------------------------
"There are no stupid Questions"
Only stupid people that don't ask them !!!!

青山 素子

Unfortunately, without access to the binaries on the server, it is near impossible to tell where the failure occurred.

For example, this is all I can make of the core file I was sent by greyknight:

Core was generated by `/usr/bin/php /REDACTED/index.php'.
Program terminated with signal 11, Segmentation fault.
[New process 8451]
#0  0x08231b91 in ?? ()


Without the right php binary (and associated shared libraries), I can't tell anything about the stack when the crash occurred, nor what might have been going on.
Motoko-chan
Director, Simple Machines

Note: Unless otherwise stated, my posts are not representative of any official position or opinion of Simple Machines.


xyxis_fahim

Ok my host said they will not deal with this because this was created by SMF script.
What can I do?

青山 素子

June 26, 2008, 12:01:47 PM #25 Last Edit: June 26, 2008, 12:06:23 PM by Motoko-chan
I don't think there is much you can do. There isn't really a way to prove to them it is not because it is not very possible to poke at the dump yourself.

I will say this, and you are welcome to quote this to your host:

Any PHP script should not cause a segmentation fault. It's rather silly to think that. If a script causes a seg fault, that means it has exposed a bug or problem in the program running it.

Why is this the case? Well, a segmentation fault is a memory violation. Specifically, when a program tries to access a non-accessible area of memory, or do something like write to a location that is "read-only". PHP and most other scripting languages can't possibly cause this because they have no control over how their parser allocates and uses memory. Rather, if this occurs while running a script, it means that particular code path the script is using has a big bug in it.

While it is not standard practice in most places to treat every core dump with a thorough investigation (at least for non-life-critical operations), recurring dumps indicate a problem that should be investigated. Given that most script parsers make use of shared libraries - particularly PHP - the fault might not be in the parser itself, but one of the libraries. This means that other applications that use this library are at risk of having problems too.

Since that many access attempts in the past involve stuff like stack smashing and crashing the application (the infamous Morris Worm crashed fingerd as an attack point), that small annoyance in the script parser might be a much larger underlying problem in the system waiting for someone to break in using it.

Remember, however, it isn't the script that is the problem, it's the actual thing crashing. Removing a script that causes segmentation violations doesn't remove the problem, it just hides the symptoms. In an analogy with the old coal-mine canary: if the canary keeps dying/passing out in the mine, you know there is a problem with the mine. The correct thing to do is to get out of there and figure how to fix the issue. You do not just get rid of the canary and venture in again.
Motoko-chan
Director, Simple Machines

Note: Unless otherwise stated, my posts are not representative of any official position or opinion of Simple Machines.


greyknight17

Thanks for all your help Motoko-chan. I guess I will be switching hosts then and hope for the best. The new host will have a more recent version of everything including Apache and PHP.

metallica48423

QuoteI then discovered that it was that small tract of code that was causing the core dumps

What code, specifically, did you establish may be causing this before?

Let us know how it goes, greyknight
Justin O'Leary
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greyknight17

The craziest thing happened these past few days. I have just been monitoring them to see if I was just lucky. They haven't been showing up anymore. As far as I know, all the versions of the software are still the same including the old Apache 1.3 version. I will ask my host to see what they changed.

MrPhil

Quote from: argimiro on June 06, 2008, 04:52:29 AM

If these files are the same issue talked about in this thread I will ask my host about it too

okay here's their reply;

Quote
The core files in your SMF forum are the corpses of programs (compiled and linked binary executables) that have upped and died. Unix-family operating systems (such as Linux) save these core files when a program dies. They contain information about the state of the machine and the program, including a snapshot of the execution stack at the moment of death. A programmer familiar with the program (and having the source code to it) can play pathologist and examine the entrails to see what was the cause of death. For anyone else, core files are useless and just take up space. For a system such as SMF, it's most likely that PHP itself died, and a systems programmer might be interested in looking at the core file to see what PHP choked on.

Cool! I'm being quoted as an authority by someone's hosting service! Or did you lift that from my posting on lunarforums.com?

MissRancher

I'm having this problem too. I ran the same version of SMF (1.1.4) on GoDaddy for a year with never a core file created. As soon as I installed on A2Hosting (through Fantastico), it's core galore.

I got this email from them:

Hello,

Your site and the other site are both dumping core with the same reason.

Core was generated by `host -W 1 99.150.196.229'.
Program terminated with signal 6, Aborted.
(gdb) backtrace
#0 0x00002aaaac432155 in raise () from /lib64/libc.so.6
#1 0x00002aaaac433bf0 in abort () from /lib64/libc.so.6
#2 0x00002aaaab61ca22 in isc_assertion_typetotext () from /usr/lib64/libisc.so.11
#3 0x00002aaaab63fda2 in isc_socketmgr_destroy () from /usr/lib64/libisc.so.11
#4 0x00002aaaac1ee307 in start_thread () from /lib64/libpthread.so.0
#5 0x00002aaaac4d3ded in clone () from /lib64/libc.so.6

The command of course runs fine from shell, but seems to be failing in the code. Do you know why or where the script may be calling the host command?

青山 素子

Quote from: MissRancher on July 17, 2008, 03:01:43 PM
The command of course runs fine from shell, but seems to be failing in the code. Do you know why or where the script may be calling the host command?

Disable hostname lookups. However, that command shouldn't be dumping core.

Also, it is recommended that you not use Fantastico for production applications. It installs some weird configs (for SMF, it forces UTF even if the server doesn't support it and it installs a ton of languages) and wants to manage updates, which it usually winds up breaking.
Motoko-chan
Director, Simple Machines

Note: Unless otherwise stated, my posts are not representative of any official position or opinion of Simple Machines.


metallica48423

July 17, 2008, 03:45:16 PM #32 Last Edit: July 17, 2008, 03:47:10 PM by metallica48423
not to mention that -- not only does it force UTF, it does so only halfway -- the Database and settings are set to UTF, but the tables remain ISO-8859-1.  This mx of collations can cause fatal errors on some MySQL setups, and will generally cause problems with characters outside the ISO-8859-1 set
Justin O'Leary
Ex-Project Manager
Ex-Lead Support Specialist

QuoteMicrosoft wants us to "Imagine life without walls"...
I say, "If there are no walls, who needs Windows?"


Useful Links:
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How to Help us Help you   
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MissRancher

Quote from: Motoko-chan on July 17, 2008, 03:42:35 PM
Disable hostname lookups. However, that command shouldn't be dumping core.

Thanks. I will post back if that does indeed fix the problem, just for a reference for anyone else.

I assume the database structure for non-Fantastico is the same as for Fantastico, so I can just export all my tables and data? I guess I'll be finding out shortly!

metallica48423

the structure is the same, yes, but the SMF installer itself properly sets the database and table collations.  However, your backup would probably be backed up with the incorrect collations :(
Justin O'Leary
Ex-Project Manager
Ex-Lead Support Specialist

QuoteMicrosoft wants us to "Imagine life without walls"...
I say, "If there are no walls, who needs Windows?"


Useful Links:
Online Manual!
How to Help us Help you   
Search
Settings Repair Tool
     

greyknight17

Hmm...thought I posted a followup on this. I asked the host what they did recently since it resolved the issue. They upgraded cPanel and recompiled Apache and PHP. That got rid of this core dump headache.

ellion

is there anything i should or could do about these core dumps.

my host is using apache 2.2.8 and php 5.2.6 but i am still getting these core dumps about 30 a day at 30mb each

青山 素子

If you have shell access, you could try to study them and see what the problem is, but otherwise only the host can do anything.
Motoko-chan
Director, Simple Machines

Note: Unless otherwise stated, my posts are not representative of any official position or opinion of Simple Machines.


ellion

i dont have shell access [not that i am aware of]
what should the host do?

青山 素子

Check the core dumps and find out what is causing them.
Motoko-chan
Director, Simple Machines

Note: Unless otherwise stated, my posts are not representative of any official position or opinion of Simple Machines.


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