[108/244] iwlegacy: fix BUG_ON(info->control.rates[0].idx < 0)

[Greg KH]

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

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

From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>

commit 7c2510120e9b43b0caf32c3786a6ab831f7d9e87 upstream.

When trying to connect to 5GHz we can provide negative index to
mac80211 what trigger BUG_ON. Reason of iwl-3945-rs malfunction
on 5GHz is unknown and needs further investigation. For now, to
do not trigger a bug, correct value and just print WARNING.

Address bug:
https://bugzilla.redhat.com/show_bug.cgi?id=730653

Reported-and-tested-by: Jan Teichmann <jan.teichmann@xxxxxxxxx>
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/net/wireless/iwlegacy/iwl-3945-rs.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/net/wireless/iwlegacy/iwl-3945-rs.c
+++ b/drivers/net/wireless/iwlegacy/iwl-3945-rs.c
@@ -822,12 +822,15 @@ static void iwl3945_rs_get_rate(void *pr
 
  out:
 
-	rs_sta->last_txrate_idx = index;
-	if (sband->band == IEEE80211_BAND_5GHZ)
-		info->control.rates[0].idx = rs_sta->last_txrate_idx -
-				IWL_FIRST_OFDM_RATE;
-	else
+	if (sband->band == IEEE80211_BAND_5GHZ) {
+		if (WARN_ON_ONCE(index < IWL_FIRST_OFDM_RATE))
+			index = IWL_FIRST_OFDM_RATE;
+		rs_sta->last_txrate_idx = index;
+		info->control.rates[0].idx = index - IWL_FIRST_OFDM_RATE;
+	} else {
+		rs_sta->last_txrate_idx = index;
 		info->control.rates[0].idx = rs_sta->last_txrate_idx;
+	}
 
 	IWL_DEBUG_RATE(priv, "leave: %d\n", index);
 }


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