Subject: [PATCH] net: ethernet: mtk_eth_soc: fix off by one check of ARRAY_SIZE
From: Tom Rix <[email-masked]>
Date: Sat, 16 Jul 2022 17:46:54 -0400

In mtk_wed_tx_ring_setup(.., int idx, ..), idx is used as an index here
  struct mtk_wed_ring *ring = &dev->tx_ring[idx];

The bounds of idx are checked here
  BUG_ON(idx > ARRAY_SIZE(dev->tx_ring));

If idx is the size of the array, it will pass this check and overflow.
So change the check to >= .

Fixes: 804775dfc288 ("net: ethernet: mtk_eth_soc: add support for Wireless Ethernet Dispatch (WED)")
Signed-off-by: Tom Rix <[email-masked]>
Link: https://lore.kernel.org/r/[email-masked]
Signed-off-by: Jakub Kicinski <[email-masked]>
---

--- a/drivers/net/ethernet/mediatek/mtk_wed.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed.c
@@ -651,7 +651,7 @@ mtk_wed_tx_ring_setup(struct mtk_wed_dev
 	 * WDMA RX.
 	 */
 
-	BUG_ON(idx > ARRAY_SIZE(dev->tx_ring));
+	BUG_ON(idx >= ARRAY_SIZE(dev->tx_ring));
 
 	if (mtk_wed_ring_alloc(dev, ring, MTK_WED_TX_RING_SIZE))
 		return -ENOMEM;