> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf
> Of Kohei Enju
> Sent: Wednesday, March 25, 2026 9:50 PM
> To: [email protected]; [email protected]
> Cc: Nguyen, Anthony L <[email protected]>; Kitszel,
> Przemyslaw <[email protected]>; Andrew Lunn
> <[email protected]>; David S. Miller <[email protected]>; Eric
> Dumazet <[email protected]>; Jakub Kicinski <[email protected]>; Paolo
> Abeni <[email protected]>; Shannon Nelson <[email protected]>; Jesse
> Brandeburg <[email protected]>; [email protected]; Kohei
> Enju <[email protected]>
> Subject: [Intel-wired-lan] [PATCH iwl-net v1] i40e: don't advertise
> IFF_SUPP_NOFCS
>
> i40e advertises IFF_SUPP_NOFCS, allowing users to use the SO_NOFCS
> socket option. However, this option is silently ignored, as the driver
> does not check skb->no_fcs, and always enables FCS insertion offload.
>
> Fix this by removing the advertisement of IFF_SUPP_NOFCS.
>
> This behavior can be reproduced with a simple AF_PACKET socket:
>
> import socket
> s = socket.socket(socket.AF_PACKET, socket.SOCK_RAW)
> s.setsockopt(socket.SOL_SOCKET, 43, 1) # SO_NOFCS
> s.bind(("eth0", 0))
> s.send(b'\xff' * 64)
>
> Previously, send() succeeds but the driver ignores SO_NOFCS.
> With this change, send() fails with -EPROTONOSUPPORT, as expected.
>
> Fixes: 41c445ff0f48 ("i40e: main driver core")
> Signed-off-by: Kohei Enju <[email protected]>
> ---
> drivers/net/ethernet/intel/i40e/i40e_main.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c
> b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index 3749f32ef95a..a3c52aa6255b 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -13831,7 +13831,6 @@ static int i40e_config_netdev(struct i40e_vsi
> *vsi)
> netdev->neigh_priv_len = sizeof(u32) * 4;
>
> netdev->priv_flags |= IFF_UNICAST_FLT;
> - netdev->priv_flags |= IFF_SUPP_NOFCS;
> /* Setup netdev TC information */
> i40e_vsi_config_netdev_tc(vsi, vsi->tc_config.enabled_tc);
>
> --
> 2.51.0
I'd recommend to add Cc: [email protected]
Reviewed-by: Aleksandr Loktionov <[email protected]>
