From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net] ipv4: igmp: guard against silly MTU values
Date: Wed, 13 Dec 2017 13:17:21 -0500 (EST)
Message-ID: <20171213.131721.876602280739964396.davem@davemloft.net>
References: <1513005459.25033.45.camel@gmail.com>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=iso-8859-1
Content-Transfer-Encoding: 8BIT
Cc: netdev@vger.kernel.org
To: eric.dumazet@gmail.com
Return-path: <netdev-owner@vger.kernel.org>
Received: from shards.monkeyblade.net ([184.105.139.130]:42098 "EHLO
        shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1753011AbdLMSRW (ORCPT
        <rfc822;netdev@vger.kernel.org>); Wed, 13 Dec 2017 13:17:22 -0500
In-Reply-To: <1513005459.25033.45.camel@gmail.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 11 Dec 2017 07:17:39 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> IPv4 stack reacts to changes to small MTU, by disabling itself under
> RTNL.
> 
> But there is a window where threads not using RTNL can see a wrong
> device mtu. This can lead to surprises, in igmp code where it is
> assumed the mtu is suitable.
> 
> Fix this by reading device mtu once and checking IPv4 minimal MTU.
> 
> This patch adds missing IPV4_MIN_MTU define, to not abuse
> ETH_MIN_MTU anymore.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied and queued up for -stable.