--- /dev/null
+From 895162b1101b3ea5db08ca6822ae9672717efec0 Mon Sep 17 00:00:00 2001
+From: Florian Westphal <fw@strlen.de>
+Date: Fri, 2 May 2014 15:32:16 +0200
+Subject: netfilter: ipv4: defrag: set local_df flag on defragmented skb
+
+From: Florian Westphal <fw@strlen.de>
+
+commit 895162b1101b3ea5db08ca6822ae9672717efec0 upstream.
+
+else we may fail to forward skb even if original fragments do fit
+outgoing link mtu:
+
+1. remote sends 2k packets in two 1000 byte frags, DF set
+2. we want to forward but only see '2k > mtu and DF set'
+3. we then send icmp error saying that outgoing link is 1500
+
+But original sender never sent a packet that would not fit
+the outgoing link.
+
+Setting local_df makes outgoing path test size vs.
+IPCB(skb)->frag_max_size, so we will still send the correct
+error in case the largest original size did not fit
+outgoing link mtu.
+
+Reported-by: Maxime Bizon <mbizon@freebox.fr>
+Suggested-by: Maxime Bizon <mbizon@freebox.fr>
+Fixes: 5f2d04f1f9 (ipv4: fix path MTU discovery with connection tracking)
+Signed-off-by: Florian Westphal <fw@strlen.de>
+Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
+Cc: Jiri Slaby <jslaby@suse.cz>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ net/ipv4/netfilter/nf_defrag_ipv4.c | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
++++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
+@@ -22,7 +22,6 @@
+ #endif
+ #include <net/netfilter/nf_conntrack_zones.h>
+
+-/* Returns new sk_buff, or NULL */
+ static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
+ {
+ int err;
+@@ -33,8 +32,10 @@ static int nf_ct_ipv4_gather_frags(struc
+ err = ip_defrag(skb, user);
+ local_bh_enable();
+
+- if (!err)
++ if (!err) {
+ ip_send_check(ip_hdr(skb));
++ skb->local_df = 1;
++ }
+
+ return err;
+ }