From 48110b4f044817a193821f42028a036feb3b8c36 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Wed, 22 Feb 2017 13:09:11 +0100
Subject: socket: do not try to create v6 socket when disabled

---
 src/compat/compat.h | 8 ++++++++
 src/socket.c        | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/src/compat/compat.h b/src/compat/compat.h
index 6a9bfd9..277e7e7 100644
--- a/src/compat/compat.h
+++ b/src/compat/compat.h
@@ -153,6 +153,14 @@ __attribute__((unused)) static inline int udp_sock_create_new(struct net *net, s
 #define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a)
 #endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 8, 0) && IS_ENABLED(CONFIG_IPV6)
+#include <net/addrconf.h>
+static inline bool ipv6_mod_enabled(void)
+{
+	return ipv6_stub->udpv6_encap_enable != NULL;
+}
+#endif
+
 /* https://lkml.org/lkml/2015/6/12/415 */
 #include <linux/netdevice.h>
 static inline struct net_device *netdev_pub(void *dev)
diff --git a/src/socket.c b/src/socket.c
index f799d91..f894cfe 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -345,6 +345,8 @@ retry:
 	rcu_assign_pointer(wg->sock4, new4->sk);
 
 #if IS_ENABLED(CONFIG_IPV6)
+	if (!ipv6_mod_enabled())
+		goto out;
 	port6.local_udp_port = htons(wg->incoming_port);
 	ret = udp_sock_create(wg->creating_net, &port6, &new6);
 	if (ret < 0) {
-- 
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