netdev - pppoe: Unshare skb before anything else

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Message-ID: <20080608062913.GA20871@gondor.apana.org.au>
Date:	Sun, 8 Jun 2008 16:29:13 +1000
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: pppoe: Unshare skb before anything else

Hi Dave:

I noticed that my last patch to move the unshare in pppoe missed
the other spot which did the same thing:

pppoe: Unshare skb before anything else

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@...dor.apana.org.au>

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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--
diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
index 58a26a4..3586d4a 100644
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -427,12 +427,12 @@ static int pppoe_disc_rcv(struct sk_buff *skb,
 	if (dev_net(dev) != &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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