[PATCH] ath9k_htc: Add a sanity check in ath9k_htc_ampdu_action()

[Dan Carpenter]

Smatch generates a warning here:

    drivers/net/wireless/ath/ath9k/htc_drv_main.c:1688 ath9k_htc_ampdu_action()
    error: buffer overflow 'ista->tid_state' 8 <= 15

I don't know if it's a real bug or not but the other paths through this
function all ensure that "tid" is less than ATH9K_HTC_MAX_TID (8) so
checking here makes things more consistent.

Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
---
This might be fine.  I see lots of other drivers don't check tid.

diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_main.c 
b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
index f808e5833d7e..a82ad739ab80 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_main.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
@@ -1683,6 +1683,10 @@ static int ath9k_htc_ampdu_action(struct ieee80211_hw 
*hw,
                ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);
                break;
        case IEEE80211_AMPDU_TX_OPERATIONAL:
+               if (tid >= ATH9K_HTC_MAX_TID) {
+                       ret = -EINVAL;
+                       break;
+               }
                ista = (struct ath9k_htc_sta *) sta->drv_priv;
                spin_lock_bh(&priv->tx.tx_lock);
                ista->tid_state[tid] = AGGR_OPERATIONAL;