linux-kernel - [PATCH net] net: dlink: fix null dereference in receive

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Message-ID: <20251009190222.4777-1-yyyynoom@gmail.com>
Date: Fri, 10 Oct 2025 04:02:22 +0900
From: Yeounsu Moon <yyyynoom@...il.com>
To: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yeounsu Moon <yyyynoom@...il.com>
Subject: [PATCH net] net: dlink: fix null dereference in receive_packet()

If `np->rx_skbuff[entry]` was not allocated before
reuse, `receive_packet()` will cause null dereference.

This patch fixes the issue by breaking out of the loop when
`np->rx_skbuff[entry]` is `NULL`.

Found by inspection.

Signed-off-by: Yeounsu Moon <yyyynoom@...il.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Tested-on: D-Link DGE-550T Rev-A3
---
 drivers/net/ethernet/dlink/dl2k.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink/dl2k.c
index 1996d2e4e3e2..aa3840454fcb 100644
--- a/drivers/net/ethernet/dlink/dl2k.c
+++ b/drivers/net/ethernet/dlink/dl2k.c
@@ -969,6 +969,8 @@ receive_packet (struct net_device *dev)
 			if (pkt_len <= copy_thresh)
 				skb = netdev_alloc_skb_ip_align(dev, pkt_len);
 			if (!skb) {
+				if (!np->rx_skbuff[entry])
+					break;
 				dma_unmap_single(&np->pdev->dev,
 						 desc_to_dma(desc),
 						 np->rx_buf_sz,
-- 
2.51.0