Bug#508432: [libnet-pcap-perl] Fwknop fails with a segmentation fault on i386

[Franck Joncourt]

> I am the upstream maintainer of both the Net::Pcap and Net::RawIP modules.

Hi,

>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=508432
>>
>> I managed with upstream to track down the problem to the
>> libnet-pcap-perl module (0.16-1).
>>
>> I have saved a typescript file[1] that shows how to reproduce the
>> problem leading to:
>>
>> [quote="syslog"]
>> Jan 12 19:47:43 diamond kernel: [822901.361529] fwknopd[30660] general
>> protection ip:f7e626c9 sp:ff9988b0 error:0 in
>> libc-2.7.so[f7df6000+138000]
>> [/quote]
> 
> I don't see anything in the typescript you pointed that would indicate
> an error. Also, I note that in this case, you were using Net::Pcap 0.05

As a matter of fact, this is not really the segmentation fault message,
this is only what I can see in my syslog, but I have previously run
fwknop in debug mode and with strace and that is quite bad :)

I have reproduced the debug mode in :
http://www.dthconnex.com/data/debug.typescript

and the strace output follow here:
http://www.dthconnex.com/data/strace.typescript

>> Here is a short explanation about what is done:
>>
>>   1/ Setup the chroot (i386 only) and install some required packages
>>   2/ Install fwknop with upstream tarball through the install.pl script.
>>      The Net::Pcap (0.05) perl module is bundled in the tarball as other
>>      perl modules.
>>   2/ Run the test suite ; it works fine.
>>   3/ Remove the Pcap.pm file (0.05)
>>   4/ Install libnet-pcap-perl (0.16-1)
>>   5/ Run the test suite ; it fails with a segmentation fault.
> 
> Did you try with compiling your own version of Net::Pcap? (I doubt this
> would be the source of the problem, but you never know) Also, do you
> have a backtrace of the segfault?

Building fwknop and all its modules within a i386 chroot (Net::Pcap
0.05), I am able to run the test suite without any error.
I have not encountered any problem before when running 0.04 (Debian
package), as well.

I have rebuilt libnet-pcap-perl (0.16) in the chroot, and run the test
suite again, and then, I get the segmentation fault message you can see
in the debug.typescript file.

The only difference I can see is the libnet-pcap-perl module, but I
should say I really do not know what's wrong.

If I can provide more informations, let me know.

>> This bug makes fwknop unusable on i386 systems.
> 
> Does this problem only happen on Debian i386 systems or can it be
> reproduced on other systems/architecture? (I'm using OSX/PowerPC).

I do have amd64/i386 chroots, and it only fails on i386.
If you want, I can give you an access to my chroots Etch/Lenny/Sid on
amd64 and i386. Unfortunately, I do not have access to a powerpc
architecture.

Is there anyone that can check if the fwknop test suite runs fine on
that architecture - http://www.dthconnex.com/data/typescript ? (Or allow
me to to do it)

Regards,

-- 
Franck Joncourt
http://debian.org - http://smhteam.info/wiki/

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