[ 079/109] gianfar: fix potential sk_wmem_alloc imbalance

[Greg Kroah-Hartman]

From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 313b037cf054ec908de92fb4c085403ffd7420d4 ]

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@xxxxxxxxxx>
Tested-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Manfred Rudigier <manfred.rudigier@xxxxxxxxxx>
Cc: Claudiu Manoil <claudiu.manoil@xxxxxxxxxxxxx>
Cc: Jiajun Wu <b06378@xxxxxxxxxxxxx>
Cc: Andy Fleming <afleming@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/freescale/gianfar.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -2065,10 +2065,9 @@ static int gfar_start_xmit(struct sk_buf
 			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;
 	}
 


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