[PATCH net v4] net: dlink: handle copy_thresh allocation failure

[PATCH net v4] net: dlink: handle copy_thresh allocation failure

[Yeounsu Moon]

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@kernel.org>
Tested-on: D-Link DGE-550T Rev-A3
Signed-off-by: Yeounsu Moon <yyyynoom@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/ethernet/dlink/dl2k.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
Changelog:
v4:
- consolidated into a single patch
- removed goto statement, per Jakub's suggestion
- reorder changelog for clarity
v3: https://lore.kernel.org/netdev/20250916183305.2808-1-yyyynoom@gmail.com/
- change confusing label name
v2: https://lore.kernel.org/netdev/20250914182653.3152-4-yyyynoom@gmail.com/
- split into two patches: whitespace cleanup and functional fix
v1: https://lore.kernel.org/netdev/20250912145339.67448-2-yyyynoom@gmail.com/
---

diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink/dl2k.c
index 6bbf6e5584e5..1996d2e4e3e2 100644
--- a/drivers/net/ethernet/dlink/dl2k.c
+++ b/drivers/net/ethernet/dlink/dl2k.c
@@ -964,15 +964,18 @@ 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,
-- 
2.51.0

Re: [PATCH net v4] net: dlink: handle copy_thresh allocation failure

[patchwork-bot+netdevbpf]

Hello:

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

On Mon, 29 Sep 2025 04:01:24 +0900 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [net,v4] net: dlink: handle copy_thresh allocation failure
    https://git.kernel.org/netdev/net/c/8169a6011c5f

You are awesome, thank you!
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