[ 59/73] ath9k: stop on rates with idx -1 in ath9k rate controls .tx_status

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pavel Roskin <redacted>

commit 2504a6423b9ab4c36df78227055995644de19edb upstream.

Rate control algorithms are supposed to stop processing when they
encounter a rate with the index -1.  Checking for rate->count not being
zero is not enough.

Allowing a rate with negative index leads to memory corruption in
ath_debug_stat_rc().

One consequence of the bug is discussed at
https://bugzilla.redhat.com/show_bug.cgi?id=768639

Signed-off-by: Pavel Roskin <redacted>
Signed-off-by: John W. Linville <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/ath/ath9k/rc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/wireless/ath/ath9k/rc.c
+++ b/drivers/net/wireless/ath/ath9k/rc.c

@@ -1328,7 +1328,7 @@ static void ath_tx_status(void *priv, st
 	fc = hdr->frame_control;
 	for (i = 0; i < sc->hw->max_rates; i++) {
 		struct ieee80211_tx_rate *rate = &tx_info->status.rates[i];
-		if (!rate->count)
+		if (rate->idx < 0 || !rate->count)
 			break;
 
 		final_ts_idx = i;