netdev - Regression in macvlan driver in stable release 4.4.209

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Message-ID: <01accb3f-bb52-906f-d164-c49f2dc170bc@cisco.com>
Date:   Mon, 20 Jan 2020 09:17:35 +0000
From:   "Hans-Christian Egtvedt (hegtvedt)" <hegtvedt@...co.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Regression in macvlan driver in stable release 4.4.209

Hello,

I am seeing a regression in the macvlan kernel driver after Linux stable 
release 4.4.209, bisecting identifies commit 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.4.y&id=8d28d7e88851b1081b05dc269a27df1c8a903f3e

There seems to be a history behind this, and I do not have the full 
overview of the intention behind the change.

What I see on my target, Aarch64 CPU, is that this patch moves the eth 
pointer in macvlan_broadcast() function some bytes. This will cause 
everything within the ethhdr struct to be wrong AFAICT.

An example:
Original code "eth = eth_hdr(skb)"
    eth = ffffffc007a1b002
New code "eth = skb_eth_hdr(skb)"
    eth = ffffffc007a1b010

Let me know if I can assist in any way.

-- 
Best regards,
Hans-Christian Noren Egtvedt