[Koha-devel] Stack Smashing

[Chadwick, John, DCA]

I had run across the SSP issue in my research which is why one of the
options on the table is to move from Ubuntu to Debian. I did build a
test box using Debian Lenny and moved the production system to that
machine. Although the stack smashing went away, we still saw the
following problems in the zebraqueue log, similar to what we were seeing
on Ubuntu.

17:56:05-07/12 zebrasrv(11) [warn] Bad magic of `dict'
17:56:05-07/12 zebrasrv(11) [warn] dict_open failed
17:56:05-07/12 zebrasrv(11) [warn] bad isamb header for file isambA
17:56:05-07/12 zebrasrv(11) [warn] isamb_open failed

The problem seems to manifest itself when using icuchains for indexing
instead of the default character mapping. Using the default.idx file for
indexing does not throw the above errors, but we lose a great deal of
functionality that is important for the patrons who will be using the
system.

I did consider setting the environment with the stack protector flag
off, but it didn't seem to make a difference. I could try the export
command instead of the environment variable. You are right, this would
not get to the underlying issues.

To test the hypothesis that the issue may be related to something with
the records or number of records, our database administrator backed out
two 500 record loads she had done late last week and started loading in
smaller chunks. She got 300 records loaded late yesterday in 100 record
chunks and we did not see any log errors or stack crashing errors. 

So, the mystery deepens.

John
-----Original Message-----
From: MJ Ray [mailto:mjr at phonecoop.coop] 
Sent: Wednesday, January 06, 2010 4:08 AM
To: Chadwick, John, DCA
Cc: koha-devel at lists.koha.org
Subject: Re: [Koha-devel] Stack Smashing

"Chadwick, John, DCA" <john.chadwick at state.nm.us> wrote: [...]
> *** stack smashing detected ***: zebraidx terminated
> ======= Backtrace: =========
> /lib/tls/i686/cmov/libc.so.6(__fortify_fail+0x48)[0xb6d7cda8]
> /lib/tls/i686/cmov/libc.so.6(__fortify_fail+0x0)[0xb6d7cd60]
> /usr/lib/libidzebra-2.0.so.0[0xb7fc10c4]
> /usr/lib/libidzebra-2.0.so.0[0xb7f69a0a]
> [0x13c]
> 
> Any ideas or suggestions would be appreciated on this one. No one has
> answered on the Zebra list.

[koha user list removed - please don't crosspost.]

Sounds like something caught by a protection system to me.  On further
searching, it seems that Ubuntu has gcc SSP enabled by default now:
https://wiki.ubuntu.com/GccSsp

It is probably best to chase this up with the Zebra list because it
looks like it is deep in libidzebra internals.  Worst case, it may
need debug versions of libc6, libidzebra and zebraidx running under
gdb to find out exactly which line of source code is causing that.

A bad fix is to rebuild libidzebra with -fno-stack-protector in
CFLAGS somehow ("export CFLAGS=-fno-stack-protector" might work)
but that won't fix any underlying cause and may well result in a
worse crash.

Hope that helps,
-- 
MJ Ray (slef)  Webmaster and LMS developer at     | software
www.software.coop http://mjr.towers.org.uk        |  .... co
IMO only: see http://mjr.towers.org.uk/email.html |  .... op

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