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Commit 3e08f4a7 authored by Steffen Klassert's avatar Steffen Klassert Committed by David S. Miller
Browse files

ip_tunnel: Fix a memory corruption in ip_tunnel_xmit 



We might extend the used aera of a skb beyond the total
headroom when we install the ipip header. Fix this by
calling skb_cow_head() unconditionally.

Bug was introduced with commit c5441932
("GRE: Refactor GRE tunneling code.")

Cc: Pravin Shelar <pshelar@nicira.com>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e024bdc0

net/ipv4/ip_tunnel.c

+6 −6
Original line number Diff line number Diff line
@@ -642,14 +642,14 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, 


	max_headroom = LL_RESERVED_SPACE(rt->dst.dev) + sizeof(struct iphdr)

			+ rt->dst.header_len;

	if (max_headroom > dev->needed_headroom) {

	if (max_headroom > dev->needed_headroom)

		dev->needed_headroom = max_headroom;



	if (skb_cow_head(skb, dev->needed_headroom)) {

		dev->stats.tx_dropped++;

		dev_kfree_skb(skb);

		return;

	}

	}



	err = iptunnel_xmit(rt, skb, fl4.saddr, fl4.daddr, protocol,

			    tos, ttl, df, !net_eq(tunnel->net, dev_net(dev)));