netdev - Re: [PATCH net 3/3] wireguard: send: account for mtu=0 devices

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Fri, 14 Feb 2020 16:56:22 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     David Miller <davem@...emloft.net>, Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net 3/3] wireguard: send: account for mtu=0 devices

On Fri, Feb 14, 2020 at 4:18 PM Eric Dumazet <eric.dumazet@...il.com> wrote:
> > However, while min_mtu=0 seems fine, it makes sense to restrict the
> > max_mtu. This commit also restricts the maximum MTU to the greatest
> > number for which rounding up to the padding multiple won't overflow a
> > signed integer. Packets this large were always rejected anyway
> > eventually, due to checks deeper in, but it seems more sound not to even
> > let the administrator configure something that won't work anyway.
> >
> If mtu is set to 0, the device must not send any payload.

Yes, but there's still internal keepalive messages.

>
> Are you sure this works ?
>
> Last statement :
>
> return padded_size - last_unit;
>
> will return a a ' negative number'

Woah nelly I don't know how I missed this. Thanks! Will send a v2 of
this patchset.