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Re: [BUG] overflow in net/ipv4/route.c rt_check_expire()

To: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [BUG] overflow in net/ipv4/route.c rt_check_expire()
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
Date: Sat, 2 Apr 2005 11:55:28 -0800
Cc: Robert.Olsson@xxxxxxxxxxx, dada1@xxxxxxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <20050402193224.GA25157@gondor.apana.org.au>
References: <E1DHdsP-0003Lr-00@gondolin.me.apana.org.au> <424E641A.1020609@cosmosbay.com> <16974.41648.568927.54429@robur.slu.se> <20050402193224.GA25157@gondor.apana.org.au>
Sender: netdev-bounce@xxxxxxxxxxx
On Sun, 3 Apr 2005 05:32:24 +1000
Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:

> On Sat, Apr 02, 2005 at 03:48:32PM +0200, Robert Olsson wrote:
> >  
> >  > Crashes usually occurs when secret_interval interval is elapsed : 
> > rt_cache_flush(0); is called, and the whole machine begins to die.
> > 
> >  A good idea to increase the secret_interval interval but it should survive.
> 
> Incidentally we should change the way the rehashing is triggered.
> Instead of doing it regularly, we can do it when we notice that a
> specific hash chain grows beyond a certain size.
> 
> The idea is that if someone is attacking our hash then they can
> only do so by lengthening the chains.  If they're not doing that
> then even if they knew how to attack us we don't really care.

Yes, the secret_interval is way too short.  It is a very paranoid
default value selected when initially fixing that DoS.

I think we should, in the short term, increase the secret interval
where it exists in the tree (netfilter conntrack is another instance
for example).

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