[3.16.y-ckt stable] Patch "inet: frags: fix defragmented packet's IP header for af_packet" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    inet: frags: fix defragmented packet's IP header for af_packet

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 6484106faa5b1a8ddaad3014d2a16f02333534c3 Mon Sep 17 00:00:00 2001
From: Edward Hyunkoo Jee <edjee at google.com>
Date: Tue, 21 Jul 2015 09:43:59 +0200
Subject: inet: frags: fix defragmented packet's IP header for af_packet

commit 0848f6428ba3a2e42db124d41ac6f548655735bf upstream.

When ip_frag_queue() computes positions, it assumes that the passed
sk_buff does not contain L2 headers.

However, when PACKET_FANOUT_FLAG_DEFRAG is used, IP reassembly
functions can be called on outgoing packets that contain L2 headers.

Also, IPv4 checksum is not corrected after reassembly.

Fixes: 7736d33f4262 ("packet: Add pre-defragmentation support for ipv4 fanouts.")
Signed-off-by: Edward Hyunkoo Jee <edjee at google.com>
Signed-off-by: Eric Dumazet <edumazet at google.com>
Cc: Willem de Bruijn <willemb at google.com>
Cc: Jerry Chu <hkchu at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv4/ip_fragment.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 8ff962d15c99..f5dad3f607d9 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -358,7 +358,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 	ihl = ip_hdrlen(skb);

 	/* Determine the position of this fragment. */
-	end = offset + skb->len - ihl;
+	end = offset + skb->len - skb_network_offset(skb) - ihl;
 	err = -EINVAL;

 	/* Is this the final fragment? */
@@ -388,7 +388,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 		goto err;

 	err = -ENOMEM;
-	if (pskb_pull(skb, ihl) == NULL)
+	if (!pskb_pull(skb, skb_network_offset(skb) + ihl))
 		goto err;

 	err = pskb_trim_rcsum(skb, end - offset);
@@ -629,6 +629,9 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 	iph->frag_off = qp->q.max_size ? htons(IP_DF) : 0;
 	iph->tot_len = htons(len);
 	iph->tos |= ecn;
+
+	ip_send_check(iph);
+
 	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS);
 	qp->q.fragments = NULL;
 	qp->q.fragments_tail = NULL;