[PATCH net] drivers: net: xgene: fix possible use after free

[Eric Dumazet]

From: Eric Dumazet <edumazet at google.com>

Once TX has been enabled on a NIC, it is illegal to access skb,
as this skb might have been freed by another cpu, from TX completion
handler.

Signed-off-by: Eric Dumazet <edumazet at google.com>
Reported-by: Mark Rutland <mark.rutland at arm.com>
Tested-by: Mark Rutland <mark.rutland at arm.com>
Cc: Iyappan Subramanian <isubramanian at apm.com>
---
 drivers/net/ethernet/apm/xgene/xgene_enet_main.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
index 1adfe7036843..9147a0107c44 100644
--- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
+++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
@@ -450,12 +450,12 @@ static netdev_tx_t xgene_enet_start_xmit(struct sk_buff *skb,
 		return NETDEV_TX_OK;
 	}
 
-	pdata->ring_ops->wr_cmd(tx_ring, count);
 	skb_tx_timestamp(skb);
 
 	pdata->stats.tx_packets++;
 	pdata->stats.tx_bytes += skb->len;
 
+	pdata->ring_ops->wr_cmd(tx_ring, count);
 	return NETDEV_TX_OK;
 }