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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Florian Westphal <fw@strlen.de>
Cc: Paolo Abeni <pabeni@redhat.com>,
	netdev@vger.kernel.org, Pablo Neira Ayuso <pablo@netfilter.org>,
	"David S. Miller" <davem@davemloft.net>,
	netfilter-devel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH net v2] netfilter: nat: cope with negative port range
Date: Wed, 14 Feb 2018 05:24:12 -0800	[thread overview]
Message-ID: <1518614652.3715.195.camel@gmail.com> (raw)
In-Reply-To: <20180214123037.GD2810@breakpoint.cc>

On Wed, 2018-02-14 at 13:30 +0100, Florian Westphal wrote:
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
> > On Wed, 2018-02-14 at 12:13 +0100, Paolo Abeni wrote:
> > > syzbot reported a division by 0 bug in the netfilter nat code:
> > > Adding the relevant check at parse time could break existing
> > > setup, moreover we would need to read/write such values atomically
> > > to avoid possible transient negative ranges at update time.
> > 
> > I do not quite follow why it is so hard to add a check at parse time.
> > 
> > Breaking buggy setups would not be a concern I think.
> 
> It would be possible for xtables but afaics in nft_nat.c case
> (nft_nat_eval) range.{min,max}_proto.all values are loaded from nft
> registers at runtime.

I prefer this explanation much more, I suggest we update the changelog
to explain the real reason.

Thanks Florian.


  reply	other threads:[~2018-02-14 13:24 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-14 11:13 [PATCH net v2] netfilter: nat: cope with negative port range Paolo Abeni
2018-02-14 12:28 ` Eric Dumazet
2018-02-14 12:30   ` Florian Westphal
2018-02-14 13:24     ` Eric Dumazet [this message]
2018-02-14 13:51     ` Pablo Neira Ayuso
2018-02-14 15:45       ` Paolo Abeni
2018-02-14 15:49         ` Pablo Neira Ayuso

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