netdev - Re: [PATCH net-next] net, bonding: Disallow vlan+srcmac with XDP

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Date:   Thu, 12 Aug 2021 18:01:34 +0300
From:   Nikolay Aleksandrov <nikolay@...dia.com>
To:     Jussi Maki <joamaki@...il.com>, netdev@...r.kernel.org
Cc:     jtoppins@...hat.com
Subject: Re: [PATCH net-next] net, bonding: Disallow vlan+srcmac with XDP

On 12/08/2021 17:52, Jussi Maki wrote:
> The new vlan+srcmac xmit policy is not implementable with XDP since
> in many cases the 802.1Q payload is not present in the packet. This
> can be for example due to hardware offload or in the case of veth
> due to use of skbuffs internally.
> 
> This also fixes the NULL deref with the vlan+srcmac xmit policy
> reported by Jonathan Toppins by additionally checking the skb
> pointer.
> 
> Fixes: a815bde56b15 ("net, bonding: Refactor bond_xmit_hash for use with xdp_buff")
> Reported-by: Jonathan Toppins <jtoppins@...hat.com>
> Signed-off-by: Jussi Maki <joamaki@...il.com>
> ---
>  drivers/net/bonding/bond_main.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 

Hi Jussi,
Could you please share the null ptr deref trace?
I'm curious how we can get a null skb at that point.

Also how are the xdp and null ptr deref changes related ?

Thanks,
 Nik