Patch "ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data and ip_finish_output" has been added to the 4.9-stable tree

Patch "ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data and ip_finish_output" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data and ip_finish_output

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ipv4-should-use-consistent-conditional-judgement-for-ip-fragment-in-__ip_append_data-and-ip_finish_output.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed Aug  9 10:32:06 PDT 2017
From: zheng li <james.z.li@ericsson.com>
Date: Mon, 12 Dec 2016 09:56:05 +0800
Subject: ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data and ip_finish_output

From: zheng li <james.z.li@ericsson.com>


[ Upstream commit 0a28cfd51e17f4f0a056bcf66bfbe492c3b99f38 ]

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 <james.z.li@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/ip_output.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -936,7 +936,7 @@ static int __ip_append_data(struct sock
 		csummode = CHECKSUM_PARTIAL;
 
 	cork->length += length;
-	if (((length > mtu) || (skb && skb_is_gso(skb))) &&
+	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 &&
 	    (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx) {


Patches currently in stable-queue which might be from james.z.li@ericsson.com are

queue-4.9/ipv4-should-use-consistent-conditional-judgement-for-ip-fragment-in-__ip_append_data-and-ip_finish_output.patch