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 <trix@redhat.com>
---
 drivers/net/ethernet/mediatek/mtk_wed.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_wed.c b/drivers/net/ethernet/mediatek/mtk_wed.c
index 8f0cd3196aac..29be2fcafea3 100644
--- 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_device *dev, int idx, void __iomem *regs)
 	 * 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;
-- 
2.27.0

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Sat, 16 Jul 2022 17:46:54 -0400 you wrote:
> 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 >= .
> 
> [...]

Here is the summary with links:
  - net: ethernet: mtk_eth_soc: fix off by one check of ARRAY_SIZE
    https://git.kernel.org/netdev/net/c/3696c952da07

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html