linux-kernel - [PATCH 3.16 245/305] mac80211: Fix mesh estab

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Message-ID: <lsq.1471110171.648399212@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Jouni Malinen" <j@...fi>,
	"Johannes Berg" <johannes@...solutions.net>
Subject: [PATCH 3.16 245/305] mac80211: Fix mesh estab_plinks counting in
 STA removal case

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Jouni Malinen <j@...fi>

commit 126e7557328a1cd576be4fca95b133a2695283ff upstream.

If a user space program (e.g., wpa_supplicant) deletes a STA entry that
is currently in NL80211_PLINK_ESTAB state, the number of established
plinks counter was not decremented and this could result in rejecting
new plink establishment before really hitting the real maximum plink
limit. For !user_mpm case, this decrementation is handled by
mesh_plink_deactive().

Fix this by decrementing estab_plinks on STA deletion
(mesh_sta_cleanup() gets called from there) so that the counter has a
correct value and the Beacon frame advertisement in Mesh Configuration
element shows the proper value for capability to accept additional
peers.

Signed-off-by: Jouni Malinen <j@...fi>
Signed-off-by: Johannes Berg <johannes@...solutions.net>
[bwh: Backported to 3.16: plink_state field is in struct sta_info]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/mac80211/mesh.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -148,14 +148,17 @@ u32 mesh_accept_plinks_update(struct iee
 void mesh_sta_cleanup(struct sta_info *sta)
 {
 	struct ieee80211_sub_if_data *sdata = sta->sdata;
-	u32 changed;
+	u32 changed = 0;

 	/*
 	 * maybe userspace handles peer allocation and peering, but in either
 	 * case the beacon is still generated by the kernel and we might need
 	 * an update.
 	 */
-	changed = mesh_accept_plinks_update(sdata);
+	if (sdata->u.mesh.user_mpm &&
+	    sta->plink_state == NL80211_PLINK_ESTAB)
+		changed |= mesh_plink_dec_estab_count(sdata);
+	changed |= mesh_accept_plinks_update(sdata);
 	if (!sdata->u.mesh.user_mpm) {
 		changed |= mesh_plink_deactivate(sta);
 		del_timer_sync(&sta->plink_timer);