netdev - Re: [Bugme-new] [Bug 11469] New: TUN with 1024 neighbours: ip6_dst_lookup

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Message-Id: <200809072119.50307.rdenis@simphalempin.com>
Date:	Sun, 7 Sep 2008 21:19:49 +0300
From:	Rémi Denis-Courmont <rdenis@...phalempin.com>
To:	Evgeniy Polyakov <johnpol@....mipt.ru>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, netdev@...r.kernel.org,
	bugme-daemon@...zilla.kernel.org
Subject: Re: [Bugme-new] [Bug 11469] New: TUN with 1024 neighbours: ip6_dst_lookup_tail NULL crash

Le dimanche 7 septembre 2008 21:11:09 Evgeniy Polyakov, vous avez écrit :
> Since dst entry is allowed not to have neighbour entry, flush it just
> like with incomplete one. This drops performance of your application
> with more than 1024 neighbours to 1024 messages, to fix it you should
> tune ipv6 routing parameters (gc intervals, gc threshold, maximum number
> of entries and so on). There may be another problem with perfomance
> though, at least I was able to bump it 10 times with different settings,
> but still two times smaller than with 4k neighbours.

That looks like a trivial local DoS against the IPv6 stack though?

Especially in the case that the interface has IFF_NOARP, that seems like a 
weird limitation. Oh well...

-- 
Rémi Denis-Courmont
http://www.remlab.net/
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