NET: ath5k, check ath5k_eeprom_mode_from_channel retval

It can, if invalid argument given, return a negative value. In that
case we would access arrays out-of-bounds and such. Check the value
and yell loudly if that happened as it would be a bug in the
implementation. (Instead of silently corrupting memory.)

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Nick Kossifidis <mickflemm@gmail.com>
Cc: "Luis R. Rodriguez" <mcgrof@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/phy.c

@@ -1613,6 +1613,10 @@ ath5k_hw_update_noise_floor(struct ath5k_hw *ah)
 	ah->ah_cal_mask |= AR5K_CALIBRATION_NF;
 
 	ee_mode = ath5k_eeprom_mode_from_channel(ah->ah_current_channel);
+	if (WARN_ON(ee_mode < 0)) {
+		ah->ah_cal_mask &= ~AR5K_CALIBRATION_NF;
+		return;
+	}
 
 	/* completed NF calibration, test threshold */
 	nf = ath5k_hw_read_measured_noise_floor(ah);

drivers/net/wireless/ath/ath5k/reset.c

@@ -985,6 +985,8 @@ ath5k_hw_commit_eeprom_settings(struct ath5k_hw *ah,
 		return;
 
 	ee_mode = ath5k_eeprom_mode_from_channel(channel);
+	if (WARN_ON(ee_mode < 0))
+		return;
 
 	/* Adjust power delta for channel 14 */
 	if (channel->center_freq == 2484)