[PATCH 1/2] ip_tunnel: fix potential issue in ip_tunnel_rcv

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

When __ip6_tnl_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/ipv6/ip6_tunnel.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 9b37f97..bf45f1b 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c

@@ -789,6 +789,9 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb,
 	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 	int err;
 
+	if (tun_dst)
+		skb_dst_set(skb, (struct dst_entry *)tun_dst);
+
 	if ((!(tpi->flags & TUNNEL_CSUM) &&
 	     (tunnel->parms.i_flags & TUNNEL_CSUM)) ||
 	    ((tpi->flags & TUNNEL_CSUM) &&

@@ -852,9 +855,6 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb,
 
 	skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(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

On Wed, 2017-06-07 at 22:16 +0800, Haishuang Yan wrote:

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>
---

Please add the missing Fixes: tag and CC author of the patch that added
this bug, so that he has a chance to comment and avoid future similar
bugs.

Thanks.

On 7 Jun 2017, at 10:48 PM, Eric Dumazet [off-list ref] wrote:

On Wed, 2017-06-07 at 22:16 +0800, Haishuang Yan wrote:

quoted

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>
---

Please add the missing Fixes: tag and CC author of the patch that added
this bug, so that he has a chance to comment and avoid future similar
bugs.

Thanks.

Ok, I will add these information in v2 commit.
Thanks.