From: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Date: Sat, 30 May 2020 15:41:31 -0400
> From: Willem de Bruijn <will...@google.com>
>
> Tun in IFF_NAPI_FRAGS mode calls napi_gro_frags. Unlike netif_rx and
> netif_gro_receive, this expects skb->data to point to the mac layer.
>
> But skb_probe_transport_header, __skb_get_hash_symmetric, and
> xdp_do_generic in tun_get_user need skb->data to point to the network
> header. Flow dissection also needs skb->protocol set, so
> eth_type_trans has to be called.
>
> Ensure the link layer header lies in linear as eth_type_trans pulls
> ETH_HLEN. Then take the same code paths for frags as for not frags.
> Push the link layer header back just before calling napi_gro_frags.
>
> By pulling up to ETH_HLEN from frag0 into linear, this disables the
> frag0 optimization in the special case when IFF_NAPI_FRAGS is used
> with zero length iov[0] (and thus empty skb->linear).
>
> Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")
> Signed-off-by: Willem de Bruijn <will...@google.com>
> Acked-by: Petar Penkov <ppen...@google.com>
Applied and queued up for -stable, thank you.
