ath9k: index out of bounds

Check whether index is within bounds before testing the element
Signed-off-by: NRoel Kluin <roel.kluin@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/rc.c

@@ -1092,8 +1092,7 @@ static int ath_rc_get_rateindex(const struct ath_rate_table *rate_table,
 	if (!(rate->flags & IEEE80211_TX_RC_MCS))
 		return rate->idx;
 
-	while (rate->idx > mcs_rix_off[i] &&
-	       i < ARRAY_SIZE(mcs_rix_off)) {
+	while (i < ARRAY_SIZE(mcs_rix_off) && rate->idx > mcs_rix_off[i]) {
 		rix++; i++;
 	}