cfg80211: Fix 160 MHz channels with 80+80 and 160 MHz drivers

The VHT supported channel width field is a two bit integer, not a
bitfield. cfg80211_chandef_usable() was interpreting it incorrectly and
ended up rejecting 160 MHz channel width if the driver indicated support
for both 160 and 80+80 MHz channels.

Cc: stable@vger.kernel.org (3.16+)
Fixes: 3d9d1d6656a73 ("nl80211/cfg80211: support VHT channel configuration")
       (however, no real drivers had 160 MHz support it until 3.16)
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/chan.c

@@ -603,7 +603,7 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
 {
 	struct ieee80211_sta_ht_cap *ht_cap;
 	struct ieee80211_sta_vht_cap *vht_cap;
-	u32 width, control_freq;
+	u32 width, control_freq, cap;
 
 	if (WARN_ON(!cfg80211_chandef_valid(chandef)))
 		return false;
@@ -643,7 +643,8 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
 			return false;
 		break;
 	case NL80211_CHAN_WIDTH_80P80:
-		if (!(vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ))
+		cap = vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
+		if (cap != IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ)
 			return false;
 	case NL80211_CHAN_WIDTH_80:
 		if (!vht_cap->vht_supported)
@@ -654,7 +655,9 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
 	case NL80211_CHAN_WIDTH_160:
 		if (!vht_cap->vht_supported)
 			return false;
-		if (!(vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ))
+		cap = vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
+		if (cap != IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ &&
+		    cap != IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ)
 			return false;
 		prohibited_flags |= IEEE80211_CHAN_NO_160MHZ;
 		width = 160;