linux-kernel - [PATCH 4.9 17/61] mac80211: dont WARN on bad WMM parameters from buggy APs

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Date:   Thu, 20 Dec 2018 10:18:17 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
        Johannes Berg <johannes.berg@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 17/61] mac80211: dont WARN on bad WMM parameters from buggy APs

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

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

[ Upstream commit c470bdc1aaf36669e04ba65faf1092b2d1c6cabe ]

Apparently, some APs are buggy enough to send a zeroed
WMM IE. Don't WARN on this since this is not caused by a bug
on the client's system.

This aligns the condition of the WARNING in drv_conf_tx
with the validity check in ieee80211_sta_wmm_params.
We will now pick the default values whenever we get
a zeroed WMM IE.

This has been reported here:
https://bugzilla.kernel.org/show_bug.cgi?id=199161

Fixes: f409079bb678 ("mac80211: sanity check CW_min/CW_max towards driver")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@...el.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mac80211/mlme.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 39451c84c785..7811650e76c4 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1867,7 +1867,8 @@ static bool ieee80211_sta_wmm_params(struct ieee80211_local *local,
 		params[ac].acm = acm;
 		params[ac].uapsd = uapsd;
 
-		if (params[ac].cw_min > params[ac].cw_max) {
+		if (params->cw_min == 0 ||
+		    params[ac].cw_min > params[ac].cw_max) {
 			sdata_info(sdata,
 				   "AP has invalid WMM params (CWmin/max=%d/%d for ACI %d), using defaults\n",
 				   params[ac].cw_min, params[ac].cw_max, aci);
-- 
2.19.1