[PATCH v2] net: ethernet: fix NULL dereference in nixge_recv()

[Ma Ke]

Due to the failure of allocating the variable 'priv' in
netdev_priv(ndev), this could result in 'priv->rx_bd_v' not being set
during the allocation process of netdev_priv(ndev), which could lead
to a null pointer dereference.

Move while() loop with 'priv->rx_bd_v' dereference after the check 
for its validity.

Found by code review.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 492caffa8a1a ("net: ethernet: nixge: Add support for National Instruments XGE netdev")
Signed-off-by: Ma Ke <make_ruc2021@xxxxxxx>
---
Changes in v2:
- modified the bug description as suggestions;
- modified the patch as the code style suggested.
---
 drivers/net/ethernet/ni/nixge.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/ni/nixge.c b/drivers/net/ethernet/ni/nixge.c
index 230d5ff99dd7..41acce878af0 100644
--- a/drivers/net/ethernet/ni/nixge.c
+++ b/drivers/net/ethernet/ni/nixge.c
@@ -604,6 +604,9 @@ static int nixge_recv(struct net_device *ndev, int budget)
 
 	cur_p = &priv->rx_bd_v[priv->rx_bd_ci];
 
+	if (!priv->rx_bd_v)
+		return 0;
+
 	while ((cur_p->status & XAXIDMA_BD_STS_COMPLETE_MASK &&
 		budget > packets)) {
 		tail_p = priv->rx_bd_p + sizeof(*priv->rx_bd_v) *
-- 
2.25.1