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Date:   Tue, 26 Nov 2019 07:49:56 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Felix Fietkau <nbd@nbd.name>
Cc:     Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>,
        Ryder Lee <ryder.lee@mediatek.com>,
        Roy Luo <royluo@google.com>, Kalle Valo <kvalo@codeaurora.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-wireless@vger.kernel.org, linux-mediatek@lists.infradead.org,
        kernel-janitors@vger.kernel.org
Subject: [PATCH] mt76: Off by one in mt76_calc_rx_airtime()
Message-ID: <20191121213935.2cbgh3qmd4hv4v5a@kili.mountain>
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The sband->bitrates[] array has "sband->n_bitrates" elements so this
check needs to be >= instead of > or we could read beyond the end of the
array.

These values come from when we call mt76_register_device():

	ret = mt76_register_device(&dev->mt76, true, mt7603_rates,
				   ARRAY_SIZE(mt7603_rates));

Here sband->bitrates[] is mt7603_rates[] and ->n_bitrates is the
ARRAY_SIZE()

Fixes: 5ce09c1a7907 ("mt76: track rx airtime for airtime fairness and survey")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/net/wireless/mediatek/mt76/airtime.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/airtime.c b/drivers/net/wireless/mediatek/mt76/airtime.c
index 55116f395f9a..a4a785467748 100644
--- a/drivers/net/wireless/mediatek/mt76/airtime.c
+++ b/drivers/net/wireless/mediatek/mt76/airtime.c
@@ -242,7 +242,7 @@ u32 mt76_calc_rx_airtime(struct mt76_dev *dev, struct mt76_rx_status *status,
 			return 0;
 
 		sband = dev->hw->wiphy->bands[status->band];
-		if (!sband || status->rate_idx > sband->n_bitrates)
+		if (!sband || status->rate_idx >= sband->n_bitrates)
 			return 0;
 
 		rate = &sband->bitrates[status->rate_idx];
-- 
2.11.0