From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Tue, 10 Jun 2008 21:08:25 +0000 (-0700)
Subject: pppoe: Unshare skb before anything else
X-Git-Tag: v2.6.26-rc6~13^2~3
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bc6cffd177f9266af38dba96a2cea06c1e7ff932;p=linux-2.6

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@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
index d89ccfd665..bafb69b6f7 100644
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -432,12 +432,12 @@ 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;