From 82a40777de12728dedf4075453b694f0d1baee80 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sun, 5 Aug 2018 22:46:07 +0800 Subject: ip6_tunnel: use the right value for ipv4 min mtu check in ip6_tnl_xmit According to RFC791, 68 bytes is the minimum size of IPv4 datagram every device must be able to forward without further fragmentation while 576 bytes is the minimum size of IPv4 datagram every device has to be able to receive, so in ip6_tnl_xmit(), 68(IPV4_MIN_MTU) should be the right value for the ipv4 min mtu check in ip6_tnl_xmit. While at it, change to use max() instead of if statement. Fixes: c9fefa08190f ("ip6_tunnel: get the min mtu properly in ip6_tnl_xmit") Reported-by: Sabrina Dubroca Signed-off-by: Xin Long Signed-off-by: David S. Miller --- net/ipv6/ip6_tunnel.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'net') diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 00e138a44cbb..1cc9650af9fb 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -1133,12 +1133,8 @@ route_lookup: max_headroom += 8; mtu -= 8; } - if (skb->protocol == htons(ETH_P_IPV6)) { - if (mtu < IPV6_MIN_MTU) - mtu = IPV6_MIN_MTU; - } else if (mtu < 576) { - mtu = 576; - } + mtu = max(mtu, skb->protocol == htons(ETH_P_IPV6) ? + IPV6_MIN_MTU : IPV4_MIN_MTU); skb_dst_update_pmtu(skb, mtu); if (skb->len - t->tun_hlen - eth_hlen > mtu && !skb_is_gso(skb)) { -- cgit v1.2.3