diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index 6d21068f9b55..7c76dd17b6b9 100644 --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -1108,8 +1108,14 @@ int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[], eth_hw_addr_random(dev); mtu = ip_tunnel_bind_dev(dev); - if (!tb[IFLA_MTU]) + if (tb[IFLA_MTU]) { + unsigned int max = 0xfff8 - dev->hard_header_len - nt->hlen; + + dev->mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU, + (unsigned int)(max - sizeof(struct iphdr))); + } else { dev->mtu = mtu; + } ip_tunnel_add(itn, nt); out: