mac80211: check ERP info IE length in parser

It's always just one byte, so check for that and
remove the length field from the parser struct.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 0f7d1c2..4839dec 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -780,8 +780,10 @@
 			elems->rsn_len = elen;
 			break;
 		case WLAN_EID_ERP_INFO:
-			elems->erp_info = pos;
-			elems->erp_info_len = elen;
+			if (elen >= 1)
+				elems->erp_info = pos;
+			else
+				elem_parse_failed = true;
 			break;
 		case WLAN_EID_EXT_SUPP_RATES:
 			elems->ext_supp_rates = pos;