mac80211: fix VHT MCS mask array overrun

The HT MCS mask has 9 bytes, the VHT one only has 8 streams.
Split the loops to handle this correctly.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -2518,15 +2518,17 @@ static int ieee80211_set_bitrate_mask(struct wiphy *wiphy,
 			continue;
 
 		for (j = 0; j < IEEE80211_HT_MCS_MASK_LEN; j++) {
-			if (~sdata->rc_rateidx_mcs_mask[i][j])
+			if (~sdata->rc_rateidx_mcs_mask[i][j]) {
 				sdata->rc_has_mcs_mask[i] = true;
-
-			if (~sdata->rc_rateidx_vht_mcs_mask[i][j])
-				sdata->rc_has_vht_mcs_mask[i] = true;
-
-			if (sdata->rc_has_mcs_mask[i] &&
-			    sdata->rc_has_vht_mcs_mask[i])
 				break;
+			}
+		}
+
+		for (j = 0; j < NL80211_VHT_NSS_MAX; j++) {
+			if (~sdata->rc_rateidx_vht_mcs_mask[i][j]) {
+				sdata->rc_has_vht_mcs_mask[i] = true;
+				break;
+			}
 		}
 	}