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    Subject[PATCH 3.18 074/185] batman-adv: fix packet checksum in receive path
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Matthias Schiffer <mschiffer@universe-factory.net>

    [ Upstream commit abd6360591d3f8259f41c34e31ac4826dfe621b8 ]

    eth_type_trans() internally calls skb_pull(), which does not adjust the
    skb checksum; skb_postpull_rcsum() is necessary to avoid log spam of the
    form "bat0: hw csum failure" when packets with CHECKSUM_COMPLETE are
    received.

    Note that in usual setups, packets don't reach batman-adv with
    CHECKSUM_COMPLETE (I assume NICs bail out of checksumming when they see
    batadv's ethtype?), which is why the log messages do not occur on every
    system using batman-adv. I could reproduce this issue by stacking
    batman-adv on top of a VXLAN interface.

    Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
    Tested-by: Maximilian Wilhelm <max@sdn.clinic>
    Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
    Signed-off-by: Sven Eckelmann <sven@narfation.org>
    Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/batman-adv/soft-interface.c | 8 +-------
    1 file changed, 1 insertion(+), 7 deletions(-)

    --- a/net/batman-adv/soft-interface.c
    +++ b/net/batman-adv/soft-interface.c
    @@ -401,13 +401,7 @@ void batadv_interface_rx(struct net_devi

    /* skb->dev & skb->pkt_type are set here */
    skb->protocol = eth_type_trans(skb, soft_iface);
    -
    - /* should not be necessary anymore as we use skb_pull_rcsum()
    - * TODO: please verify this and remove this TODO
    - * -- Dec 21st 2009, Simon Wunderlich
    - */
    -
    - /* skb->ip_summed = CHECKSUM_UNNECESSARY; */
    + skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);

    batadv_inc_counter(bat_priv, BATADV_CNT_RX);
    batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,

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