net: fec: fix potential use after free

skb_tx_timestamp(skb) should be called _before_ TX completion
has a chance to trigger, otherwise it is too late and we access
freed memory.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: de5fb0a05348 ("net: fec: put tx to napi poll function to fix dead lock")
Cc: Frank Li <Frank.Li@freescale.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index e7c8b749c5a5..50bb71c663e2 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -428,6 +428,8 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
         /* If this was the last BD in the ring, start at the beginning again. */
         bdp = fec_enet_get_nextdesc(bdp, fep);
 
+        skb_tx_timestamp(skb);
+
         fep->cur_tx = bdp;
 
         if (fep->cur_tx == fep->dirty_tx)
@@ -436,8 +438,6 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
         /* Trigger transmission start */
         writel(0, fep->hwp + FEC_X_DES_ACTIVE);
 
-        skb_tx_timestamp(skb);
-
         return NETDEV_TX_OK;
 }