netdev - Re: [net-next PATCH] bpf/cpumap: make sure frame_size for build

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Date:   Thu, 20 Dec 2018 23:25:46 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org
Subject: Re: [net-next PATCH] bpf/cpumap: make sure frame_size for build_skb
 is aligned if headroom isn't

On 12/19/2018 05:00 PM, Jesper Dangaard Brouer wrote:
> The frame_size passed to build_skb must be aligned, else it is
> possible that the embedded struct skb_shared_info gets unaligned.
> 
> For correctness make sure that xdpf->headroom in included in the
> alignment. No upstream drivers can hit this, as all XDP drivers provide
> an aligned headroom.  This was discovered when playing with implementing
> XDP support for mvneta, which have a 2 bytes DSA header, and this
> Marvell ARM64 platform didn't like doing atomic operations on an
> unaligned skb_shinfo(skb)->dataref addresses.
> 
> Fixes: 1c601d829ab0 ("bpf: cpumap xdp_buff to skb conversion and allocation")
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>

Applied to bpf-next, thanks!