[PATCH 4.9 44/47] mac80211: minstrel: fix tx status processing corner case

[Greg Kroah-Hartman]

From: Felix Fietkau <nbd@xxxxxxxx>

commit b2911a84396f72149dce310a3b64d8948212c1b3 upstream.

Some drivers fill the status rate list without setting the rate index after
the final rate to -1. minstrel_ht already deals with this, but minstrel
doesn't, which causes it to get stuck at the lowest rate on these drivers.

Fix this by checking the count as well.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: cccf129f820e ("mac80211: add the 'minstrel' rate control algorithm")
Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
Link: https://lore.kernel.org/r/20201111183359.43528-3-nbd@xxxxxxxx
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/mac80211/rc80211_minstrel.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -274,7 +274,7 @@ minstrel_tx_status(void *priv, struct ie
 	success = !!(info->flags & IEEE80211_TX_STAT_ACK);
 
 	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
-		if (ar[i].idx < 0)
+		if (ar[i].idx < 0 || !ar[i].count)
 			break;
 
 		ndx = rix_to_ndx(mi, ar[i].idx);