4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paolo Abeni <pabeni@xxxxxxxxxx>
[ Upstream commit ccfec9e5cb2d48df5a955b7bf47f7782157d3bc2]
Cong noted that we need the same checks introduced by commit 76c0ddd8c3a6
("ip6_tunnel: be careful when accessing the inner header")
even for ipv4 tunnels.
Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
Suggested-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/ip_tunnel.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -627,6 +627,7 @@ void ip_tunnel_xmit(struct sk_buff *skb,
const struct iphdr *tnl_params, u8 protocol)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
+ unsigned int inner_nhdr_len = 0;
const struct iphdr *inner_iph;
struct flowi4 fl4;
u8 tos, ttl;
@@ -636,6 +637,14 @@ void ip_tunnel_xmit(struct sk_buff *skb,
__be32 dst;
bool connected;
+ /* ensure we can access the inner net header, for several users below */
+ if (skb->protocol == htons(ETH_P_IP))
+ inner_nhdr_len = sizeof(struct iphdr);
+ else if (skb->protocol == htons(ETH_P_IPV6))
+ inner_nhdr_len = sizeof(struct ipv6hdr);
+ if (unlikely(!pskb_may_pull(skb, inner_nhdr_len)))
+ goto tx_error;
+
inner_iph = (const struct iphdr *)skb_inner_network_header(skb);
connected = (tunnel->parms.iph.daddr != 0);
