[PATCH 4.18 023/168] mac80211: mesh: fix HWMP sequence numbering to follow standard

[Greg Kroah-Hartman]

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

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

From: Yuan-Chi Pang <fu3mo6goo@xxxxxxxxx>

[ Upstream commit 1f631c3201fe5491808df143d8fcba81b3197ffd ]

IEEE 802.11-2016 14.10.8.3 HWMP sequence numbering says:
If it is a target mesh STA, it shall update its own HWMP SN to
maximum (current HWMP SN, target HWMP SN in the PREQ element) + 1
immediately before it generates a PREP element in response to a
PREQ element.

Signed-off-by: Yuan-Chi Pang <fu3mo6goo@xxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/mac80211/mesh_hwmp.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -572,6 +572,10 @@ static void hwmp_preq_frame_process(stru
 		forward = false;
 		reply = true;
 		target_metric = 0;
+
+		if (SN_GT(target_sn, ifmsh->sn))
+			ifmsh->sn = target_sn;
+
 		if (time_after(jiffies, ifmsh->last_sn_update +
 					net_traversal_jiffies(sdata)) ||
 		    time_before(jiffies, ifmsh->last_sn_update)) {