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From:   Masashi Honma <masashi.honma@gmail.com>
To:     johannes@sipsolutions.net
Cc:     linux-wireless@vger.kernel.org,
        Masashi Honma <masashi.honma@gmail.com>
Subject: [PATCH] nl80211: Disallow setting of HT for channel 14
Date:   Mon, 21 Oct 2019 16:50:45 +0900
Message-Id: <20191021075045.2719-1-masashi.honma@gmail.com>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

This patch disables setting of HT20 and more for channel 14 because
the channel is only for IEEE 802.11b.

The patch for net/wireless/util.c was unit-tested.

The patch for net/wireless/chan.c was tested with iw command.

Before this patch.
$ sudo iw dev <ifname> set channel 14 HT20
$

After this patch.
$ sudo iw dev <ifname> set channel 14 HT20
kernel reports: invalid channel definition
command failed: Invalid argument (-22)
$

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
---
 net/wireless/chan.c | 4 ++++
 net/wireless/util.c | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index e851cafd8e2f..1212deb41361 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -204,6 +204,10 @@ bool cfg80211_chandef_valid(const struct cfg80211_chan_def *chandef)
 		return false;
 	}
 
+	/* channel 14 is only for IEEE 802.11b */
+	if (chandef->center_freq1 == 2484 && chandef->width > NL80211_CHAN_WIDTH_20_NOHT)
+		return false;
+
 	if (cfg80211_chandef_is_edmg(chandef) &&
 	    !cfg80211_edmg_chandef_valid(chandef))
 		return false;
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 419eb12c1e93..063715df3950 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1559,7 +1559,8 @@ bool ieee80211_chandef_to_operating_class(struct cfg80211_chan_def *chandef,
 	}
 
 	if (freq == 2484) {
-		if (chandef->width > NL80211_CHAN_WIDTH_40)
+		/* channel 14 is only for IEEE 802.11b */
+		if (chandef->width > NL80211_CHAN_WIDTH_20_NOHT)
 			return false;
 
 		*op_class = 82; /* channel 14 */
-- 
2.17.1