cfg80211: DFS check dfs_region before usage

Check the DFS region before channel availability check.
Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -5651,8 +5651,13 @@ static int nl80211_start_radar_detection(struct sk_buff *skb,
 	struct net_device *dev = info->user_ptr[1];
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct cfg80211_chan_def chandef;
+	enum nl80211_dfs_regions dfs_region;
 	int err;
 
+	dfs_region = reg_get_dfs_region(wdev->wiphy);
+	if (dfs_region == NL80211_DFS_UNSET)
+		return -EINVAL;
+
 	err = nl80211_parse_chandef(rdev, info, &chandef);
 	if (err)
 		return err;