linux-kernel - Re: [PATCH] net: Reset skb to network header in neigh_hh

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Message-ID: <1475874656.28155.268.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Sat, 08 Oct 2016 06:10:56 +0900
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Abdelrhman Ahmed <ab@...hmed.com>
Cc:     davem <davem@...emloft.net>, netdev <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: Reset skb to network header in neigh_hh_output

On Fri, 2016-10-07 at 16:14 +0200, Abdelrhman Ahmed wrote:
> When hardware header is added without using cached one, neigh_resolve_output
> and neigh_connected_output reset skb to network header before adding it.
> When cached one is used, neigh_hh_output does not reset the skb to network
> header.
> 
> The fix is to reset skb to network header before adding cached hardware header
> to keep the behavior consistent in all cases.

What is the issue you want to fix exactly ?

Please describe the use case.

I highly suggest you take a look at commit

e1f165032c8bade3a6bdf546f8faf61fda4dd01c
("net: Fix skb_under_panic oops in neigh_resolve_output")

Otherwise, your fix is in fact adding a critical bug.