Re: kernel stack trace using conntrack

[Eric Dumazet <eric.dumazet@gmail.com>]

Le vendredi 19 février 2010 à 03:18 +0100, Pablo Neira Ayuso a écrit :
> Patrick McHardy wrote:
> > Pablo Neira Ayuso wrote:
> >> Patrick McHardy wrote:
> >>>>> Pablo, please let me know whether you want me to apply this.
> >>>> ctnetlink_change_helper() also calls nf_ct_ext_add() for conntracks that
> >>>> are confirmed (in case of a helper update for an existing conntrack).
> >>>> That would also trigger the assertion. If we want to support helper
> >>>> assignation via ctnetlink for existing conntracks, we will need to add
> >>>> locking to the conntrack extension infrastructure to avoid races.
> >>>>
> >>>> I don't see a clear solution for this yet.
> >>> I see, this is indeed a problem. Since the helper is known at the
> >>> first event, we could restrict this to only allow manual assignment
> >>> for newly created conntracks. Most helpers probably can't properly
> >>> cope with connections not seen from the beginning anyways.
> >> Indeed, changing the helper in the middle of the road doesn't make too
> >> much sense to me either. I can send you a patch for this along today,
> >> I'll find some spare time to do it.
> > 
> > Great, thanks Pablo.
> 
> I have slightly tested the following patch here. I think it should fix
> the problem.
> 
> We can revisit ctnetlink_change_helper() later, I think there's some
> code there that can be refactorized.
> 
> Let me know if you're OK with it.

I sucessfuly tested your patch Pablo, thanks.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>