Patch "vti6: Don't report path MTU below IPV6_MIN_MTU." has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    vti6: Don't report path MTU below IPV6_MIN_MTU.

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:
     vti6-don-t-report-path-mtu-below-ipv6_min_mtu.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 Tue Dec 12 13:26:17 CET 2017
From: Steffen Klassert <steffen.klassert@secunet.com>
Date: Wed, 15 Feb 2017 11:38:58 +0100
Subject: vti6: Don't report path MTU below IPV6_MIN_MTU.

From: Steffen Klassert <steffen.klassert@secunet.com>


[ Upstream commit e3dc847a5f85b43ee2bfc8eae407a7e383483228 ]

In vti6_xmit(), the check for IPV6_MIN_MTU before we
send a ICMPV6_PKT_TOOBIG message is missing. So we might
report a PMTU below 1280. Fix this by adding the required
check.

Fixes: ccd740cbc6e ("vti6: Add pmtu handling to vti6_xmit.")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv6/ip6_vti.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -485,11 +485,15 @@ vti6_xmit(struct sk_buff *skb, struct ne
 	if (!skb->ignore_df && skb->len > mtu) {
 		skb_dst(skb)->ops->update_pmtu(dst, NULL, skb, mtu);
 
-		if (skb->protocol == htons(ETH_P_IPV6))
+		if (skb->protocol == htons(ETH_P_IPV6)) {
+			if (mtu < IPV6_MIN_MTU)
+				mtu = IPV6_MIN_MTU;
+
 			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
-		else
+		} else {
 			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 				  htonl(mtu));
+		}
 
 		return -EMSGSIZE;
 	}


Patches currently in stable-queue which might be from steffen.klassert@secunet.com are

queue-4.9/xfrm-copy-policy-family-in-clone_policy.patch
queue-4.9/vti6-don-t-report-path-mtu-below-ipv6_min_mtu.patch