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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Vasily Khoruzhick <vasilykh@arista.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.18 11/88] neighbour: confirm neigh entries when ARP packet is received
Date:   Thu, 27 Sep 2018 11:02:52 +0200
Message-Id: <20180927090301.886411335@linuxfoundation.org>
In-Reply-To: <20180927090300.631426620@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

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

From: Vasily Khoruzhick <vasilykh@arista.com>

[ Upstream commit f0e0d04413fcce9bc76388839099aee93cd0d33b ]

Update 'confirmed' timestamp when ARP packet is received. It shouldn't
affect locktime logic and anyway entry can be confirmed by any higher-layer
protocol. Thus it makes sense to confirm it when ARP packet is received.

Fixes: 77d7123342dc ("neighbour: update neigh timestamps iff update is effective")
Signed-off-by: Vasily Khoruzhick <vasilykh@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/neighbour.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1179,6 +1179,12 @@ int neigh_update(struct neighbour *neigh
 		lladdr = neigh->ha;
 	}
 
+	/* Update confirmed timestamp for neighbour entry after we
+	 * received ARP packet even if it doesn't change IP to MAC binding.
+	 */
+	if (new & NUD_CONNECTED)
+		neigh->confirmed = jiffies;
+
 	/* If entry was valid and address is not changed,
 	   do not change entry state, if new one is STALE.
 	 */
@@ -1200,15 +1206,12 @@ int neigh_update(struct neighbour *neigh
 		}
 	}
 
-	/* Update timestamps only once we know we will make a change to the
+	/* Update timestamp only once we know we will make a change to the
 	 * neighbour entry. Otherwise we risk to move the locktime window with
 	 * noop updates and ignore relevant ARP updates.
 	 */
-	if (new != old || lladdr != neigh->ha) {
-		if (new & NUD_CONNECTED)
-			neigh->confirmed = jiffies;
+	if (new != old || lladdr != neigh->ha)
 		neigh->updated = jiffies;
-	}
 
 	if (new != old) {
 		neigh_del_timer(neigh);