arc_emac: fix potential use after free

Signed-off-by: Eric Dumazet <edumazet@google.com>
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.

Fixes: e4f2379db6c6 ("ethernet/arc/arc_emac - Add new driver")
From: Eric Dumazet <edumazet@google.com>
Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
index b2ffad1304d221ef54e60cd1a82138a4d8344975..248baf6273fb76a2b179c50fe068aeddff51a42e 100644 (file)
--- a/drivers/net/ethernet/arc/emac_main.c
+++ b/drivers/net/ethernet/arc/emac_main.c
@@ -565,6 +565,8 @@ static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
        /* Make sure pointer to data buffer is set */
        wmb();
 
+       skb_tx_timestamp(skb);
+
        *info = cpu_to_le32(FOR_EMAC | FIRST_OR_LAST_MASK | len);
 
        /* Increment index to point to the next BD */
@@ -579,8 +581,6 @@ static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
 
        arc_reg_set(priv, R_STATUS, TXPL_MASK);
 
-       skb_tx_timestamp(skb);
-
        return NETDEV_TX_OK;
 }