[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 9293c82..7e21342 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -899,17 +899,9 @@
/* 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;
+ if (skb_cow_head(skb, PPP_HDRLEN))
+ goto outf;
- 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;
- }
pp = skb_push(skb, 2);
proto = npindex_to_proto[npi];
pp[0] = proto >> 8;