[PATCH] mac80211: minstrel: avoid accessing negative indices in rix_to_ndx()

If rix is not found in mi->r[], i will become -1 after the loop.  This value
is eventually used to access arrays, so we were accessing arrays with a
negative index, which is obviously not what we want to do.  This patch fixes
this potential problem.

Signed-off-by: Luciano Coelho <luciano.coelho@...>
---
 net/mac80211/rc80211_minstrel.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
index b218b98..e2dd248 100644
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -66,7 +66,7 @@ rix_to_ndx(struct minstrel_sta_info *mi, int rix)
 	for (i = rix; i >= 0; i--)
 		if (mi->r[i].rix == rix)
 			break;
-	WARN_ON(mi->r[i].rix != rix);
+	WARN_ON(i < 0 || mi->r[i].rix != rix);
 	return i;
 }

@@ -181,6 +181,9 @@ minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
 			break;

 		ndx = rix_to_ndx(mi, ar[i].idx);
+		if (ndx < 0)
+			continue;
+
 		mi->r[ndx].attempts += ar[i].count;

 		if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
--

-- 
1.6.0.4

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