ip_gre: remove the incorrect mtu limit for ipgre tap

[ Upstream commit cfddd4c33c254954927942599d299b3865743146 ]

ipgre tap driver calls ether_setup(), after commit 61e84623ace3
("net: centralize net_device min/max MTU checking"), the range
of mtu is [min_mtu, max_mtu], which is [68, 1500] by default.

It causes the dev mtu of the ipgre tap device to not be greater
than 1500, this limit value is not correct for ipgre tap device.

Besides, it's .change_mtu already does the right check. So this
patch is just to set max_mtu as 0, and leave the check to it's
.change_mtu.

Fixes: 61e84623ace3 ("net: centralize net_device min/max MTU checking")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 0453312..1933654 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1274,6 +1274,7 @@ static const struct net_device_ops erspan_netdev_ops = {
 static void ipgre_tap_setup(struct net_device *dev)
 {
        ether_setup(dev);
+       dev->max_mtu = 0;
        dev->netdev_ops = &gre_tap_netdev_ops;
        dev->priv_flags &= ~IFF_TX_SKB_SHARING;
        dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;