ipv6: Should use consistent conditional judgement for ip6 fragment between __ip6_appe...

There is an inconsistent conditional judgement between __ip6_append_data
and ip6_finish_output functions, the variable length in __ip6_append_data
just include the length of application's payload and udp6 header, don't
include the length of ipv6 header, but in ip6_finish_output use
(skb->len > ip6_skb_dst_mtu(skb)) as judgement, and skb->len include the
length of ipv6 header.

That causes some particular application's udp6 payloads whose length are
between (MTU - IPv6 Header) and MTU were fragmented by ip6_fragment even
though the rst->dev support UFO feature.

Add the length of ipv6 header to length in __ip6_append_data to keep
consistent conditional judgement as ip6_finish_output for ip6 fragment.

Signed-off-by: Zheng Li <james.z.li@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name ipv6-should-use-consistent-conditional-judgement-for.patch

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 1ac3cea491713c0eaaf529e722e9babc30727c30..094e91123cbfd46ac13d32a5a528360310e923b0 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1371,7 +1371,7 @@ emsgsize:
         */
 
        cork->length += length;
-       if (((length > mtu) ||
+       if ((((length + fragheaderlen) > mtu) ||
             (skb && skb_is_gso(skb))) &&
            (sk->sk_protocol == IPPROTO_UDP) &&
            (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&