klibc - Aug 2010 - Bug#584583: [PATCH] Additional fix for ipconfig

[ adding relevant cc's ]

On Tue, 10 Aug 2010, Julien-externe BLACHE wrote:
> Hi,
> 
> Attached is a second patch for ipconfig, which further improves (actually, 
> restores) ipconfig's behaviour on busy LANs with UDP noise.
> 
> Commit 4efbcf90f60e27febe883ef052454d8cfded5c15 really is the root of all 
> evil, it badly broke ipconfig by doing a lot of changes all over the place 
> that were not warranted and badly tested.
Indeed as mailinglist history show I had been sceptic to that monster
patch, but several users had pushed for it, see:
http://bugs.debian.org/511959
 
> After this commit, if a random UDP packet comes in before the expected 
> DHCP reply packet_recv() will exit with an error and the interface will be 
> sent into DEVST_ERROR instead of just ignoring this packet. On busy LANs, 
> ipconfig can go through this loop several times.
> 
> JB.
as mika is currently on vacation after Debconf. I will look into the issue
and see if said patch resolves his testcase which is nicely layed out in
http://bugs.debian.org/552554

thank you for the patch.

-- 
maks

max at stro.at wrote on 08/12/2010 08:00:21 PM:

Hi,
> > Commit 4efbcf90f60e27febe883ef052454d8cfded5c15 really is the root of 
all 
> > evil, it badly broke ipconfig by doing a lot of changes all over the 
place 
> > that were not warranted and badly tested.
> 
> Indeed as mailinglist history show I had been sceptic to that monster
> patch, but several users had pushed for it, see:
> http://bugs.debian.org/511959
I think KiBi got bitten by the bug described in the commit message for 
4efbcf, where the next packet would be discarded as packet_discard() ended 
up being called twice for some codepath.

However I have a hard time believing that commit did fix the issue 
reliably for KiBi's setup. If it did, I believe I wouldn't have had any 
problems in my setup.
> as mika is currently on vacation after Debconf. I will look into the 
issue
> and see if said patch resolves his testcase which is nicely layed out in
> http://bugs.debian.org/552554
He told me he'd try it out next week and report back. In the meantime, I 
have the patched ipconfig in production and it's working even better than 
1.5.12 did, so I'm really confident those patches fix ipconfig for good. 
Actually we haven't had a single failure with that patched version and 
interface configuration happens immediately.
> thank you for the patch.
You're welcome. Just to make sure, both patches are needed. Even with the 
second patch applied, there are still cases where the interface can go 
into DEVST_ERROR and enter an infinite loop due to this missing case in 
the first switch() statement. I think it would mostly happen on machines 
with more than one interface when running ipconfig on all interfaces. It 
falls in the "obviously correct even if unneeded" category, anyway.

JB.

-- 
Consultant INTM - Debian Developer - TMI Calibre
EDF - DSP - CSP IT - ITS Rh?ne Alpes - C4S - CCNPS
04 69 65 68 56



Ce message et toutes les pi?ces jointes (ci-apr?s le 'Message') sont
?tablis ? l'intention exclusive des destinataires et les informations qui y
figurent sont strictement confidentielles. Toute utilisation de ce Message non
conforme ? sa destination, toute diffusion ou toute publication totale ou
partielle, est interdite sauf autorisation expresse.

Si vous n'?tes pas le destinataire de ce Message, il vous est interdit de le
copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou partie.
Si vous avez re?u ce Message par erreur, merci de le supprimer de votre syst?me,
ainsi que toutes ses copies, et de n'en garder aucune trace sur quelque
support que ce soit. Nous vous remercions ?galement d'en avertir
imm?diatement l'exp?diteur par retour du message.

Il est impossible de garantir que les communications par messagerie ?lectronique
arrivent en temps utile, sont s?curis?es ou d?nu?es de toute erreur ou virus.
____________________________________________________

This message and any attachments (the 'Message') are intended solely for
the addressees. The information contained in this Message is confidential. Any
use of information contained in this Message not in accord with its purpose, any
dissemination or disclosure, either whole or partial, is prohibited except
formal approval.

If you are not the addressee, you may not copy, forward, disclose or use any
part of it. If you have received this message in error, please delete it and all
copies from your system and notify the sender immediately by return message.

E-mail communication cannot be guaranteed to be timely secure, error or
virus-free.