From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Sun, 16 Sep 2007 23:21:42 +0000 (-0700)
Subject: [PPP] generic: Call skb_cow_head before scribbling over skb
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=7b797d5b150775d717cb03b5ada28b8bad99afab;p=linux-beck.git

[PPP] generic: Call skb_cow_head before scribbling over skb

It's rude to write over data that other people are still using.  So call
skb_cow_head before PPP proceeds to modify the skb data.

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

diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 9293c82ef2af..7e21342becb2 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -899,17 +899,9 @@ ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	/* Put the 2-byte PPP protocol number on the front,
 	   making sure there is room for the address and control fields. */
-	if (skb_headroom(skb) < PPP_HDRLEN) {
-		struct sk_buff *ns;
-
-		ns = alloc_skb(skb->len + dev->hard_header_len, GFP_ATOMIC);
-		if (ns == 0)
-			goto outf;
-		skb_reserve(ns, dev->hard_header_len);
-		skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
-		kfree_skb(skb);
-		skb = ns;
-	}
+	if (skb_cow_head(skb, PPP_HDRLEN))
+		goto outf;
+
 	pp = skb_push(skb, 2);
 	proto = npindex_to_proto[npi];
 	pp[0] = proto >> 8;