[PATCH 1/8] ipv6: xfrm6: release dst on error in xfrm6_rcv_encap()

[Steffen Klassert <steffen.klassert@secunet.com>]

From: Yilin Zhu <zylzyl2333@gmail.com>

xfrm6_rcv_encap() performs an IPv6 route lookup when the skb does not
already have a dst attached. ip6_route_input_lookup() returns a
referenced dst entry even when the lookup resolves to an error route.

If dst->error is set, xfrm6_rcv_encap() drops the skb without attaching
the dst to the skb and without releasing the reference returned by the
lookup. Repeated packets hitting this path therefore leak dst entries.

Release the dst before jumping to the drop path.

Fixes: 0146dca70b87 ("xfrm: add support for UDPv6 encapsulation of ESP")
Cc: stable@kernel.org
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Co-developed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Yuan Tan <yuantan098@gmail.com>
Suggested-by: Xin Liu <bird@lzu.edu.cn>
Tested-by: Ruide Cao <caoruide123@gmail.com>
Signed-off-by: Yilin Zhu <zylzyl2333@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/ipv6/xfrm6_protocol.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/xfrm6_protocol.c b/net/ipv6/xfrm6_protocol.c
index ea2f805d3b01..9b586fcec485 100644
--- a/net/ipv6/xfrm6_protocol.c
+++ b/net/ipv6/xfrm6_protocol.c
@@ -88,8 +88,10 @@ int xfrm6_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
 
 		dst = ip6_route_input_lookup(dev_net(skb->dev), skb->dev, &fl6,
 					     skb, flags);
-		if (dst->error)
+		if (dst->error) {
+			dst_release(dst);
 			goto drop;
+		}
 		skb_dst_set(skb, dst);
 	}
 
-- 
2.43.0