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 c544193214
("GRE: Refactor GRE tunneling code.")
Cc: Pravin Shelar <pshelar@nicira.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -642,14 +642,14 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
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max_headroom = LL_RESERVED_SPACE(rt->dst.dev) + sizeof(struct iphdr)
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+ rt->dst.header_len;
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if (max_headroom > dev->needed_headroom) {
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if (max_headroom > dev->needed_headroom)
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dev->needed_headroom = max_headroom;
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if (skb_cow_head(skb, dev->needed_headroom)) {
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dev->stats.tx_dropped++;
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dev_kfree_skb(skb);
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return;
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}
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}
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err = iptunnel_xmit(rt, skb, fl4.saddr, fl4.daddr, protocol,
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tos, ttl, df, !net_eq(tunnel->net, dev_net(dev)));
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