netdev - Re: [PATCH net v2] netfilter: nat: cope with negative port range

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Message-ID: <1518611306.3715.193.camel@gmail.com>
Date:   Wed, 14 Feb 2018 04:28:26 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        netfilter-devel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH net v2] netfilter: nat: cope with negative port range

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.