[PATCH net] udp_tunnel: don't treat IPv4 sockets bound to an address as wildcard

[Antonio Quartulli <antonio@mandelbit.com>]

With IPv6 enabled, sk_saddr_any() checks sk_v6_rcv_saddr also for
AF_INET sockets, where it is always zero. An IPv4 tunnel socket bound to
a specific address (e.g. fou or geneve with "local") ends up in the GRO
lookup fast path, although another socket may bind the same port on a
different address: GRO then hands that socket's packets to the tunnel's
gro_receive.

Check the IPv6 address only for AF_INET6 sockets.

Fixes: a36283e2b683 ("udp_tunnel: create a fastpath GRO lookup.")
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
---
 net/ipv4/udp_tunnel_core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/udp_tunnel_core.c b/net/ipv4/udp_tunnel_core.c
index a128fe85620d..29581c94fdcf 100644
--- a/net/ipv4/udp_tunnel_core.c
+++ b/net/ipv4/udp_tunnel_core.c
@@ -62,10 +62,10 @@ EXPORT_SYMBOL(udp_sock_create4);
 static bool sk_saddr_any(struct sock *sk)
 {
 #if IS_ENABLED(CONFIG_IPV6)
-	return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
-#else
-	return !sk->sk_rcv_saddr;
+	if (sk->sk_family == AF_INET6)
+		return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
 #endif
+	return !sk->sk_rcv_saddr;
 }
 
 void setup_udp_tunnel_sock(struct net *net, struct sock *sk,
-- 
2.56.0