netdev - Re: "TCP: eth0: Driver has suspect GRO implementation, TCP performance may be compromised." message with "ethtool -K eth0 gro off"

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

Message-ID: <20170310122208.GA293@x4>
Date:   Fri, 10 Mar 2017 13:22:08 +0100
From:   Markus Trippelsdorf <markus@...ppelsdorf.de>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Subject: Re: "TCP: eth0: Driver has suspect GRO implementation, TCP
 performance may be compromised." message with "ethtool -K eth0 gro off"

On 2017.02.06 at 19:12 -0200, Marcelo Ricardo Leitner wrote:
> On Fri, Feb 03, 2017 at 06:47:33AM -0800, Eric Dumazet wrote:
> > On Fri, 2017-02-03 at 12:28 -0200, Marcelo Ricardo Leitner wrote:
> > 
> > > Aren't you mixing the endpoints here? MSS is the largest amount of data
> > > that the peer can receive in a single segment, and not how much it will
> > > send. For the sending part, that depends on what the other peer
> > > announced, and we can have 2 different MSS in a single connection, one
> > > for each peer.
> > > 
> > > If a peer later wants to send larger segments, it can, but it must
> > > respect the mss advertised by the other peer during handshake.
> > > 
> > 
> > I am not mixing endpoints, you are.
> > 
> > If you need to be convinced, please grab :
> > https://patchwork.ozlabs.org/patch/723028/
> > 
> > And just watch "ss -temoi ..." 
> 
> I still don't get it, but I also hit the warning on my laptop, using
> iwlwifi. Not sure what I did in order to trigger it, it was by accident.

I am running with your debugging patch applied since the beginning of
February and was not able to reproduce the issue ever again.
So I think your code is innocent and another bug (,that seems to be
fixed since then) somehow caused the kernel to jump to the function.

-- 
Markus