gianfar: fix potential sk_wmem_alloc imbalance

commit db83d136d7f753 (gianfar: Fix missing sock reference when
processing TX time stamps) added a potential sk_wmem_alloc imbalance

If the new skb has a different truesize than old one, we can get a
negative sk_wmem_alloc once new skb is orphaned at TX completion.

Now we no longer early orphan skbs in dev_hard_start_xmit(), this
probably can lead to fatal bugs.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Manfred Rudigier <manfred.rudigier@omicron.at>
Cc: Claudiu Manoil <claudiu.manoil@freescale.com>
Cc: Jiajun Wu <b06378@freescale.com>
Cc: Andy Fleming <afleming@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 4 deletions

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index f2db8fca46a1..ab1d80ff0791 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -2063,10 +2063,9 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
                         return NETDEV_TX_OK;
                 }
 
-                /* Steal sock reference for processing TX time stamps */
-                swap(skb_new->sk, skb->sk);
-                swap(skb_new->destructor, skb->destructor);
-                kfree_skb(skb);
+                if (skb->sk)
+                        skb_set_owner_w(skb_new, skb->sk);
+                consume_skb(skb);
                 skb = skb_new;
         }