netdev - [solved] Re: skb->protocol 0x300?!

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Message-ID: <b9abff38-54af-6773-9a8c-77d847837388@tarent.de>
Date:   Sun, 3 Jul 2022 19:51:02 +0200 (CEST)
From:   Thorsten Glaser <t.glaser@...ent.de>
To:     netdev@...r.kernel.org
Subject: [solved] Re: skb->protocol 0x300?!

On Fri, 1 Jul 2022, Thorsten Glaser wrote:

> Now I’m getting 0x300 in skb->protocol for what tcpdump -X makes
> me believe is a fragmented IP packet.

I also get it for unfragmented packets, and the kernel source does
not ever set it, which got me on the right track for searching.

Turns out that the buster-backports kernel has the fix already:
https://lore.kernel.org/netdev/20190318053952.115180-1-komachi.yoshiki@lab.ntt.co.jp/t/
describes my problem, and booting into 5.10 instead of 4.19 gives
me the correct skb->protocol value.

bye,
//mirabilos
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