[PATCH net] net: dlink: fix null dereference in receive_packet()

[Yeounsu Moon <yyyynoom@gmail.com>]

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@gmail.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