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From:   =?UTF-8?q?Micha=C5=82=20Lowas-Rzechonek?= 
        <michal.lowas-rzechonek@silvair.com>
To:     linux-bluetooth@vger.kernel.org
Subject: [PATCH BlueZ] mesh: Fix IV Recovery procedure when IV Update is in progress
Date:   Thu,  5 Sep 2019 15:12:40 +0200
Message-Id: <20190905131240.24969-1-michal.lowas-rzechonek@silvair.com>
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Sender: linux-bluetooth-owner@vger.kernel.org
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This fixes erroneously cleared sequence number when node performs IV
Recovery procedure on startup in a following scenario:
     - node has IV Index set to <N>
     - node starts in IV_UPD_INIT state
     - node receives a Secure Network Beacon with IV Index <N>+1 and IV
       Update flag set

Upon reception, the node shall:
    - increase its IV Index to <N>+1
    - enter IV_UPD_UPDATING state

This means that the node keeps transmitting messages using IV Index
equal to <N>, therefore it shall not reset its Sequence Number before IV
Update procedure completes.

If, on the other hand, received Secure Network Beacon contains IV Index
<N>+2 (or more), the node shall:
    - increase its IV Index to <N>+2 (or more)
    - enter IV_UPD_UPDATING state
    - reset the Sequence Number to 0
---
 mesh/net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mesh/net.c b/mesh/net.c
index 2785039db..b4b390541 100644
--- a/mesh/net.c
+++ b/mesh/net.c
@@ -2735,7 +2735,7 @@ static void update_iv_kr_state(struct mesh_subnet *subnet, uint32_t iv_index,
 	}
 
 	if (net->iv_upd_state == IV_UPD_INIT) {
-		if (iv_index > net->iv_index)
+		if (iv_index > net->iv_index + 1)
 			mesh_net_set_seq_num(net, 0);
 		net->iv_index = iv_index;
 
-- 
2.19.1