linux-kernel - Re: [PATCH net] tipc: check minimum bearer MTU

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Date:   Thu, 1 Dec 2016 18:07:47 +0800
From:   Ying Xue <ying.xue@...driver.com>
To:     Michal Kubecek <mkubecek@...e.cz>
CC:     Jon Maloy <jon.maloy@...csson.com>,
        "David S. Miller" <davem@...emloft.net>,
        <tipc-discussion@...ts.sourceforge.net>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Ben Hutchings <ben@...adent.org.uk>,
        Qian Zhang <zhangqian-c@....cn>
Subject: Re: [PATCH net] tipc: check minimum bearer MTU

>>
>> For UDP bearer, it seems insufficient for us to check MTU size only
>> when UDP bearer is enabled. Meanwhile, we should update MTU size for
>> UDP bearer with Path MTU discovery protocol once MTU size is changed
>> after bearer is enabled.
>
> I should admit I'm not that familiar with tipc. Do you mean updating
> b->mtu in response to PMTU updates of the route used for ub->ubsock?

Yes.

> The way I understand it, it would be certainly useful but it's not
> directly related to the security issue this patch addresses as if there
> are no updates, b->mtu cannot get too low and there is no risk of
> a buffer overflow. In other words, reflecting PMTU updates is something
> that can be IMHO left for later.
>

Agreed.

Regards,
Ying

>                                                       Michal Kubecek
>