linux-kernel - Re: [PATCH net] ipvlan: Ignore PACKET_LOOPBACK in handle_mode

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Message-ID: <eb26c4db-5219-4ee6-b49d-fb324742266d@redhat.com>
Date: Thu, 4 Dec 2025 13:52:02 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Dmitry Skorodumov <skorodumov.dmitry@...wei.com>, netdev@...r.kernel.org,
 Jakub Kicinski <kuba@...nel.org>, Julian Vetter <julian@...er-limits.org>,
 Guillaume Nault <gnault@...hat.com>, Eric Dumazet <edumazet@...gle.com>,
 Mahesh Bandewar <maheshb@...gle.com>, "David S. Miller"
 <davem@...emloft.net>, linux-kernel@...r.kernel.org
Cc: Andrew Lunn <andrew+netdev@...n.ch>
Subject: Re: [PATCH net] ipvlan: Ignore PACKET_LOOPBACK in handle_mode_l2()

On 12/2/25 11:39 AM, Dmitry Skorodumov wrote:
> Packets with pkt_type == PACKET_LOOPBACK are captured by
> handle_frame() function, but they don't have L2 header.
> We should not process them in handle_mode_l2().
> 
> This doesn't affect old L2 functionality, since handling
> was anyway incorrect.
> 
> Handle them the same way as in br_handle_frame():
> just pass the skb.
> 
> To observe invalid behaviour, just start "ping -b" on bcast address
> of port-interface.
> 
> Fixes: 2ad7bf363841 ("ipvlan: Initial check-in of the IPVLAN driver.")
> Signed-off-by: Dmitry Skorodumov <skorodumov.dmitry@...wei.com>

Since you appear the have momentum on ipvlan devel, please consider
adding self-tests for the issue you are addressing.

You can later leverage the same infra for functional coverage and that
will help your intended development.

Thanks,

Paolo