From: zheng li Date: Mon, 12 Dec 2016 01:56:05 +0000 (+0800) Subject: ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data... X-Git-Tag: v3.16.48~20 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c52f61de88947adfb9d35b7de3dabfee8ef6e7b1;p=linux ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data and ip_finish_output commit 0a28cfd51e17f4f0a056bcf66bfbe492c3b99f38 upstream. There is an inconsistent conditional judgement in __ip_append_data and ip_finish_output functions, the variable length in __ip_append_data just include the length of application's payload and udp header, don't include the length of ip header, but in ip_finish_output use (skb->len > ip_skb_dst_mtu(skb)) as judgement, and skb->len include the length of ip header. That causes some particular application's udp payload whose length is between (MTU - IP Header) and MTU were fragmented by ip_fragment even though the rst->dev support UFO feature. Add the length of ip header to length in __ip_append_data to keep consistent conditional judgement as ip_finish_output for ip fragment. Signed-off-by: Zheng Li Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context to apply after "udp: consistently apply ufo or fragmentation"] Signed-off-by: Ben Hutchings --- diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index d813da85bdaa..f05dde98873e 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -886,7 +886,7 @@ static int __ip_append_data(struct sock *sk, cork->length += length; if ((skb && skb_is_gso(skb)) || - ((length > mtu) && + (((length + fragheaderlen) > mtu) && (skb_queue_len(queue) <= 1) && (sk->sk_protocol == IPPROTO_UDP) && (rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) &&