I don't know where this value comes from (probably a copy and paste and paste and paste ...). Let's use standard values which are a bit greater.
Link: https://git.kernel.org/pub/scm/linux/kernel/git/davem/netdev-vger-cvs.git/commit/?id=e5afd356a411a Signed-off-by: Nicolas Dichtel <nicolas.dich...@6wind.com> --- net/ipv6/ip6_tunnel.c | 11 ++++++++--- net/ipv6/sit.c | 5 +++-- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index da66aaac51ce..00e138a44cbb 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -1692,8 +1692,13 @@ int ip6_tnl_change_mtu(struct net_device *dev, int new_mtu) if (new_mtu < ETH_MIN_MTU) return -EINVAL; } - if (new_mtu > 0xFFF8 - dev->hard_header_len) - return -EINVAL; + if (tnl->parms.proto == IPPROTO_IPV6 || tnl->parms.proto == 0) { + if (new_mtu > IP6_MAX_MTU - dev->hard_header_len) + return -EINVAL; + } else { + if (new_mtu > IP_MAX_MTU - dev->hard_header_len) + return -EINVAL; + } dev->mtu = new_mtu; return 0; } @@ -1841,7 +1846,7 @@ ip6_tnl_dev_init_gen(struct net_device *dev) if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT)) dev->mtu -= 8; dev->min_mtu = ETH_MIN_MTU; - dev->max_mtu = 0xFFF8 - dev->hard_header_len; + dev->max_mtu = IP6_MAX_MTU - dev->hard_header_len; return 0; diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 2afce37a7177..e9400ffa7875 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -1371,7 +1371,7 @@ static void ipip6_tunnel_setup(struct net_device *dev) dev->hard_header_len = LL_MAX_HEADER + t_hlen; dev->mtu = ETH_DATA_LEN - t_hlen; dev->min_mtu = IPV6_MIN_MTU; - dev->max_mtu = 0xFFF8 - t_hlen; + dev->max_mtu = IP6_MAX_MTU - t_hlen; dev->flags = IFF_NOARP; netif_keep_dst(dev); dev->addr_len = 4; @@ -1583,7 +1583,8 @@ static int ipip6_newlink(struct net *src_net, struct net_device *dev, if (tb[IFLA_MTU]) { u32 mtu = nla_get_u32(tb[IFLA_MTU]); - if (mtu >= IPV6_MIN_MTU && mtu <= 0xFFF8 - dev->hard_header_len) + if (mtu >= IPV6_MIN_MTU && + mtu <= IP6_MAX_MTU - dev->hard_header_len) dev->mtu = mtu; } -- 2.15.1
