linux-kernel - [PATCH 5.10] net: dlink: handle copy

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Message-ID: <20251105122550.1497-1-drtrosh@yandex-team.ru>
Date: Wed,  5 Nov 2025 15:25:50 +0300
From: Andrey Troshin <drtrosh@...dex-team.ru>
To: stable@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Andrey Troshin <drtrosh@...dex-team.ru>,
	Steve French <sfrench@...ba.org>,
	linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [PATCH 5.10] net: dlink: handle copy_thresh allocation failure

From: Yeounsu Moon <yyyynoom@...il.com>

[ Upstream commit 8169a6011c5fecc6cb1c3654c541c567d3318de8 ]

The driver did not handle failure of `netdev_alloc_skb_ip_align()`.
If the allocation failed, dereferencing `skb->protocol` could lead to
a NULL pointer dereference.

This patch tries to allocate `skb`. If the allocation fails, it falls
back to the normal path.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Suggested-by: Jakub Kicinski <kuba@...nel.org>
Tested-on: D-Link DGE-550T Rev-A3
Signed-off-by: Yeounsu Moon <yyyynoom@...il.com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Link: https://patch.msgid.link/20250928190124.1156-1-yyyynoom@gmail.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
[Andrey Troshin: fixe merge conflicts]
Signed-off-by: Andrey Troshin <drtrosh@...dex-team.ru>
---
Backport fix for CVE-2025-40053
Link: https://nvd.nist.gov/vuln/detail/CVE-2025-40053
---
 drivers/net/ethernet/dlink/dl2k.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink/dl2k.c
index af1e96e0209f..0af58c4dcebc 100644
--- a/drivers/net/ethernet/dlink/dl2k.c
+++ b/drivers/net/ethernet/dlink/dl2k.c
@@ -957,15 +957,18 @@ receive_packet (struct net_device *dev)
 		} else {
 			struct sk_buff *skb;
 
+			skb = NULL;
 			/* Small skbuffs for short packets */
-			if (pkt_len > copy_thresh) {
+			if (pkt_len <= copy_thresh)
+				skb = netdev_alloc_skb_ip_align(dev, pkt_len);
+			if (!skb) {
 				dma_unmap_single(&np->pdev->dev,
 						 desc_to_dma(desc),
 						 np->rx_buf_sz,
 						 DMA_FROM_DEVICE);
 				skb_put (skb = np->rx_skbuff[entry], pkt_len);
 				np->rx_skbuff[entry] = NULL;
-			} else if ((skb = netdev_alloc_skb_ip_align(dev, pkt_len))) {
+			} else {
 				dma_sync_single_for_cpu(&np->pdev->dev,
 							desc_to_dma(desc),
 							np->rx_buf_sz,
-- 
2.34.1