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Diffstat (limited to 'net')
-rw-r--r--net/l2tp/l2tp_ppp.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index f42cd0915966..8a90d756c904 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -395,6 +395,7 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 	struct pppol2tp_session *ps;
 	int old_headroom;
 	int new_headroom;
+	int uhlen, headroom;
 
 	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
 		goto abort;
@@ -413,7 +414,13 @@ static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
 		goto abort_put_sess;
 
 	old_headroom = skb_headroom(skb);
-	if (skb_cow_head(skb, sizeof(ppph)))
+	uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
+	headroom = NET_SKB_PAD +
+		   sizeof(struct iphdr) + /* IP header */
+		   uhlen +		/* UDP header (if L2TP_ENCAPTYPE_UDP) */
+		   session->hdr_len +	/* L2TP header */
+		   sizeof(ppph);	/* PPP header */
+	if (skb_cow_head(skb, headroom))
 		goto abort_put_sess_tun;
 
 	new_headroom = skb_headroom(skb);