ovpn: fix ndo_start_xmit return value on error

ndo_start_xmit is basically expected to always return NETDEV_TX_OK.
However, in case of error, it was currently returning NET_XMIT_DROP,
which is not a valid netdev_tx_t return value, leading to
misinterpretation.

Change ndo_start_xmit to always return NETDEV_TX_OK to signal back
to the caller that the packet was handled (even if dropped).

Effects of this bug can be seen when sending IPv6 packets having
no peer to forward them to:

  $ ip netns exec ovpn-server oping -c20 fd00:abcd:220:201::1
  PING fd00:abcd:220:201::1 (fd00:abcd:220:201::1) 56 bytes of data.00:abcd:220:201 :1
  ping_send failed: No buffer space available
  ping_sendto: No buffer space available
  ping_send failed: No buffer space available
  ping_sendto: No buffer space available
  ...

Fixes: c2d950c4672a ("ovpn: add basic interface creation/destruction/management routines")
Reported-by: Gert Doering <gert@greenie.muc.de>
Closes: https://github.com/OpenVPN/ovpn-net-next/issues/5
Tested-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Gert Doering <gert@greenie.muc.de>
Link: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31591.html
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>

diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c
index 7e4b89484c9d4b95386eebe3dbb4d96c65f72dc1..43f428ac112e6429883bc60a022f4d106cb75318 100644 (file)
--- a/drivers/net/ovpn/io.c
+++ b/drivers/net/ovpn/io.c
@@ -410,7 +410,7 @@ drop:
        dev_dstats_tx_dropped(ovpn->dev);
        skb_tx_error(skb);
        kfree_skb_list(skb);
-       return NET_XMIT_DROP;
+       return NETDEV_TX_OK;
 }
 
 /**