linux-kernel - [PATCH] net: dl2k: fix potential null deref in receive

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Message-Id: <20250321121352.29750-1-qasdev00@gmail.com>
Date: Fri, 21 Mar 2025 12:13:52 +0000
From: Qasim Ijaz <qasdev00@...il.com>
To: andrew+netdev@...n.ch,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	yyyynoom@...il.com,
	horms@...nel.org
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] net: dl2k: fix potential null deref in receive_packet()

If the pkt_len is less than the copy_thresh the netdev_alloc_skb_ip_align()
is called to allocate an skbuff, on failure it can return NULL. Since
there is no NULL check a NULL deref can occur when setting
skb->protocol.

Fix this by introducing a NULL check to handle allocation failure.

Fixes: 89d71a66c40d ("net: Use netdev_alloc_skb_ip_align()")
Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
---
 drivers/net/ethernet/dlink/dl2k.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink/dl2k.c
index d0ea92607870..22e9432adea0 100644
--- a/drivers/net/ethernet/dlink/dl2k.c
+++ b/drivers/net/ethernet/dlink/dl2k.c
@@ -968,6 +968,11 @@ receive_packet (struct net_device *dev)
 							   np->rx_buf_sz,
 							   DMA_FROM_DEVICE);
 			}
+
+			if (unlikely(!skb)) {
+				np->rx_ring[entry].fraginfo = 0;
+				break;
+			}
 			skb->protocol = eth_type_trans (skb, dev);
 #if 0
 			/* Checksum done by hw, but csum value unavailable. */
-- 
2.39.5