[patch 6/9] pppoe: Unshare skb before anything else

[Greg KH]

2.6.25-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit bc6cffd177f9266af38dba96a2cea06c1e7ff932 ]

We need to unshare the skb first as otherwise pskb_may_pull may
write to a shared skb which could be bad.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/net/pppoe.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -432,12 +432,12 @@ static int pppoe_disc_rcv(struct sk_buff
 	if (dev->nd_net != &init_net)
 		goto abort;
 
-	if (!pskb_may_pull(skb, sizeof(struct pppoe_hdr)))
-		goto abort;
-
 	if (!(skb = skb_share_check(skb, GFP_ATOMIC)))
 		goto out;
 
+	if (!pskb_may_pull(skb, sizeof(struct pppoe_hdr)))
+		goto abort;
+
 	ph = pppoe_hdr(skb);
 	if (ph->code != PADT_CODE)
 		goto abort;

-- 
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