From: Li Wei <lw@cn.fujitsu.com>
Date: Thu, 29 Jan 2015 08:09:03 +0000 (+0800)
Subject: ipv4: Don't increase PMTU with Datagram Too Big message.
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=3cdaa5be9e81;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

ipv4: Don't increase PMTU with Datagram Too Big message.

RFC 1191 said, "a host MUST not increase its estimate of the Path
MTU in response to the contents of a Datagram Too Big message."

Signed-off-by: Li Wei <lw@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index d58dd0ec3e53..52e1f2bf0ca2 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -966,6 +966,9 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 	if (dst->dev->mtu < mtu)
 		return;
 
+	if (rt->rt_pmtu && rt->rt_pmtu < mtu)
+		return;
+
 	if (mtu < ip_rt_min_pmtu)
 		mtu = ip_rt_min_pmtu;