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Commit 09df57ca authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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l2tp: give proper headroom in pppol2tp_xmit() 



pppol2tp_xmit() calls skb_cow_head(skb, 2) before calling
l2tp_xmit_skb()

Then l2tp_xmit_skb() calls again skb_cow_head(skb, large_headroom)

This patchs changes the first skb_cow_head() call to supply the needed
headroom to make sure at most one (expensive) pskb_expand_head() is
done.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bc416d97

net/l2tp/l2tp_ppp.c

+8 −1
Original line number Diff line number Diff line
@@ -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);