cfg80211: validate IBSS BSSID

The IBSS BSSID is never validated, so an
invalid one might end up being used. Fix
this by rejecting invalid configuration.
Reported-by: NMarek Lindner <lindner_marek@yahoo.de>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/wireless/nl80211.c

@@ -4527,8 +4527,12 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
 
 	wiphy = &rdev->wiphy;
 
-	if (info->attrs[NL80211_ATTR_MAC])
+	if (info->attrs[NL80211_ATTR_MAC]) {
 		ibss.bssid = nla_data(info->attrs[NL80211_ATTR_MAC]);
+
+		if (!is_valid_ether_addr(ibss.bssid))
+			return -EINVAL;
+	}
 	ibss.ssid = nla_data(info->attrs[NL80211_ATTR_SSID]);
 	ibss.ssid_len = nla_len(info->attrs[NL80211_ATTR_SSID]);