This is a note to let you know that I've just added the patch titled ip6_gre: init dev->mtu and dev->hard_header_len correctly to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ip6_gre-init-dev-mtu-and-dev-hard_header_len-correctly.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sun Jan 28 17:35:08 CET 2018 From: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx> Date: Thu, 18 Jan 2018 20:51:12 +0300 Subject: ip6_gre: init dev->mtu and dev->hard_header_len correctly From: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx> [ Upstream commit 128bb975dc3c25d00de04e503e2fe0a780d04459 ] Commit b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") moved dev->mtu initialization from ip6gre_tunnel_setup() to ip6gre_tunnel_init(), as a result, the previously set values, before ndo_init(), are reset in the following cases: * rtnl_create_link() can update dev->mtu from IFLA_MTU parameter. * ip6gre_tnl_link_config() is invoked before ndo_init() in netlink and ioctl setup, so ndo_init() can reset MTU adjustments with the lower device MTU as well, dev->mtu and dev->hard_header_len. Not applicable for ip6gretap because it has one more call to ip6gre_tnl_link_config(tunnel, 1) in ip6gre_tap_init(). Fix the first case by updating dev->mtu with 'tb[IFLA_MTU]' parameter if a user sets it manually on a device creation, and fix the second one by moving ip6gre_tnl_link_config() call after register_netdevice(). Fixes: b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") Fixes: db2ec95d1ba4 ("ip6_gre: Fix MTU setting") Signed-off-by: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv6/ip6_gre.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -337,11 +337,12 @@ static struct ip6_tnl *ip6gre_tunnel_loc nt->dev = dev; nt->net = dev_net(dev); - ip6gre_tnl_link_config(nt, 1); if (register_netdevice(dev) < 0) goto failed_free; + ip6gre_tnl_link_config(nt, 1); + /* Can use a lockless transmit, unless we generate output sequences */ if (!(nt->parms.o_flags & TUNNEL_SEQ)) dev->features |= NETIF_F_LLTX; @@ -1307,7 +1308,6 @@ static void ip6gre_netlink_parms(struct static int ip6gre_tap_init(struct net_device *dev) { - struct ip6_tnl *tunnel; int ret; ret = ip6gre_tunnel_init_common(dev); @@ -1316,10 +1316,6 @@ static int ip6gre_tap_init(struct net_de dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; - tunnel = netdev_priv(dev); - - ip6gre_tnl_link_config(tunnel, 1); - return 0; } @@ -1411,12 +1407,16 @@ static int ip6gre_newlink(struct net *sr nt->dev = dev; nt->net = dev_net(dev); - ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]); err = register_netdevice(dev); if (err) goto out; + ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]); + + if (tb[IFLA_MTU]) + ip6_tnl_change_mtu(dev, nla_get_u32(tb[IFLA_MTU])); + dev_hold(dev); ip6gre_tunnel_link(ign, nt); Patches currently in stable-queue which might be from alexey.kodanev@xxxxxxxxxx are queue-4.14/dccp-don-t-restart-ccid2_hc_tx_rto_expire-if-sk-in-closed-state.patch queue-4.14/ip6_gre-init-dev-mtu-and-dev-hard_header_len-correctly.patch