# \[PATCH 1/2\] ip\_tunnel: fix potential issue in ip\_tunnel\_rcv

- From: Haishuang Yan \<hidden\>
- Date: 2017-06-07 14:16:30 
- List: netdev
- Page: https://ratatoskr.run/netdev/2017/06/5014700
- Thread: https://ratatoskr.run/netdev/2017/06/5014700/t.md

```text
When ip_tunnel_rcv fails, the tun_dst won't be freed, so move
skb_dst_set to begin and tun_dst would be freed by kfree_skb.

Signed-off-by: Haishuang Yan <redacted>
---
 net/ipv4/ip_tunnel.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index b878ecb..27fc20f 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -386,6 +386,9 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
 	const struct iphdr *iph = ip_hdr(skb);
 	int err;
 
+	if (tun_dst)
+		skb_dst_set(skb, (struct dst_entry *)tun_dst);
+
 #ifdef CONFIG_NET_IPGRE_BROADCAST
 	if (ipv4_is_multicast(iph->daddr)) {
 		tunnel->dev->stats.multicast++;
@@ -439,9 +442,6 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
 		skb->dev = tunnel->dev;
 	}
 
-	if (tun_dst)
-		skb_dst_set(skb, (struct dst_entry *)tun_dst);
-
 	gro_cells_receive(&tunnel->gro_cells, skb);
 	return 0;
 
-- 
1.8.3.1
```