linux-kernel - [PATCH 4.16 49/55] ipv4: reset fnhe_mtu

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Message-Id: <20180518081459.708662342@linuxfoundation.org>
Date:   Fri, 18 May 2018 10:15:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.16 49/55] ipv4: reset fnhe_mtu_locked after cache route flushed

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hangbin Liu <liuhangbin@...il.com>

[ Upstream commit 0e8411e426e277f55bd21e287ec89fab6f8eacae ]

After route cache is flushed via ipv4_sysctl_rtcache_flush(), we forget
to reset fnhe_mtu_locked in rt_bind_exception(). When pmtu is updated
in __ip_rt_update_pmtu(), it will return directly since the pmtu is
still locked. e.g.

+ ip netns exec client ping 10.10.1.1 -c 1 -s 1400 -M do
PING 10.10.1.1 (10.10.1.1) 1400(1428) bytes of data.
>>From 10.10.0.254 icmp_seq=1 Frag needed and DF set (mtu = 0)

Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/route.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1376,6 +1376,7 @@ static bool rt_bind_exception(struct rta
 			fnhe->fnhe_gw = 0;
 			fnhe->fnhe_pmtu = 0;
 			fnhe->fnhe_expires = 0;
+			fnhe->fnhe_mtu_locked = false;
 			fnhe_flush_routes(fnhe);
 			orig = NULL;
 		}