netdev - Re: [PATCH net] ping: fix the dif and sdif check in ping

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Date:   Wed, 23 Feb 2022 07:52:51 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, davem <davem@...emloft.net>,
        Vasiliy Kulikov <segoon@...nwall.com>
Subject: Re: [PATCH net] ping: fix the dif and sdif check in ping_lookup

On Wed, 23 Feb 2022 14:08:06 +0800 Xin Long wrote:
> On Thu, Feb 17, 2022 at 11:57 PM Jakub Kicinski <kuba@...nel.org> wrote:
> > Are you sure this is not reachable from some networking path allowing
> > attacker (or local user) to DoS the kernel logs?  
> Hi, Jakub, sorry for late.
> 
> I actually didn't see how a skb with protocol != IP/IPV6 could reach here.
> ping_err() is using "BUG()" for this kind of case.
> I added this 'else' branch mostly to avoid the possible compiling
> warning for "Use of uninitialized value dif/sdif".

Understood but it's best practice to avoid prints on the datapath.
We should either drop the print completely (given it's impossible)
or make it _once.