ath5k: Fix range scaling when setting rate power table

rates[i] is unsigned but txp_offset can be negative for newer parts
with PDADC table. We cover the case when rates[i] + txp_offset > 63
but we must also cover the case when its < 0 or else rates[i] will overflow.

Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath5k/phy.c b/drivers/net/wireless/ath/ath5k/phy.c
index aa1a77d4cd90..84a9aafd91a2 100644
--- a/drivers/net/wireless/ath/ath5k/phy.c
+++ b/drivers/net/wireless/ath/ath5k/phy.c
@@ -3516,6 +3516,7 @@ ath5k_setup_rate_powertable(struct ath5k_hw *ah, u16 max_pwr,
 {
         unsigned int i;
         u16 *rates;
+        s16 rate_idx_scaled = 0;
 
         /* max_pwr is power level we got from driver/user in 0.5dB
          * units, switch to 0.25dB units so we can compare */
@@ -3580,10 +3581,13 @@ ath5k_setup_rate_powertable(struct ath5k_hw *ah, u16 max_pwr,
          * match the power range set by user with the power indices
          * on PCDAC/PDADC table */
         for (i = 0; i < 16; i++) {
-                rates[i] += ah->ah_txpower.txp_offset;
+                rate_idx_scaled = rates[i] + ah->ah_txpower.txp_offset;
                 /* Don't get out of bounds */
-                if (rates[i] > 63)
-                        rates[i] = 63;
+                if (rate_idx_scaled > 63)
+                        rate_idx_scaled = 63;
+                if (rate_idx_scaled < 0)
+                        rate_idx_scaled = 0;
+                rates[i] = rate_idx_scaled;
         }
 }