[PATCH v2 net] net: ethernet: mediatek: avoid potential invalid memory access

From: Sean Wang <sean.wang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>

Potential dangerous invalid memory might be accessed if invalid mac value
reflected from the forward port field in rxd4 caused by possible potential
hardware defects. So added a simple sanity checker to avoid the kind of
situation happening.

Signed-off-by: Sean Wang <sean.wang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
Acked-by: John Crispin <redacted>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index c1dc08c..e69524c 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -999,6 +999,10 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 		      RX_DMA_FPORT_MASK;
 		mac--;
 
+		if (unlikely(mac < 0 || mac >= MTK_MAC_COUNT ||
+			     !eth->netdev[mac]))
+			goto release_desc;
+
 		netdev = eth->netdev[mac];
 
 		if (unlikely(test_bit(MTK_RESETTING, &eth->state)))

-- 
2.7.4

From: <sean.wang@mediatek.com>
Date: Sat, 22 Jul 2017 20:45:55 +0800

From: Sean Wang <sean.wang@mediatek.com>

Potential dangerous invalid memory might be accessed if invalid mac value
reflected from the forward port field in rxd4 caused by possible potential
hardware defects. So added a simple sanity checker to avoid the kind of
situation happening.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Acked-by: John Crispin <john@phrozen.org>

Applied.