From: Eric Dumazet <edumazet@google.com>
Date: Wed, 31 Mar 2021 21:38:11 +0000 (-0700)
Subject: ipv6: remove extra dev_hold() for fallback tunnels
X-Git-Tag: v4.4.269~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c5534ba6d4a6bec37ee7849b3c32f0ec31aba691;p=thirdparty%2Fkernel%2Fstable.git

ipv6: remove extra dev_hold() for fallback tunnels

commit 0d7a7b2014b1a499a0fe24c9f3063d7856b5aaaf upstream.

My previous commits added a dev_hold() in tunnels ndo_init(),
but forgot to remove it from special functions setting up fallback tunnels.

Fallback tunnels do call their respective ndo_init()

This leads to various reports like :

unregister_netdevice: waiting for ip6gre0 to become free. Usage count = 2

Fixes: 48bb5697269a ("ip6_tunnel: sit: proper dev_{hold|put} in ndo_[un]init methods")
Fixes: 6289a98f0817 ("sit: proper dev_{hold|put} in ndo_[un]init methods")
Fixes: 40cb881b5aaa ("ip6_vti: proper dev_{hold|put} in ndo_[un]init methods")
Fixes: 7f700334be9a ("ip6_gre: proper dev_{hold|put} in ndo_[un]init methods")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 6efe6b101d3f7..23e6a845c7fa9 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -350,7 +350,6 @@ static struct ip6_tnl *ip6gre_tunnel_locate(struct net *net,
 	if (!(nt->parms.o_flags & GRE_SEQ))
 		dev->features |= NETIF_F_LLTX;
 
-	dev_hold(dev);
 	ip6gre_tunnel_link(ign, nt);
 	return nt;
 
@@ -1310,8 +1309,6 @@ static void ip6gre_fb_tunnel_init(struct net_device *dev)
 	strcpy(tunnel->parms.name, dev->name);
 
 	tunnel->hlen		= sizeof(struct ipv6hdr) + 4;
-
-	dev_hold(dev);
 }
 
 
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 478baeb08951f..80f88df280d7a 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1614,7 +1614,6 @@ static int __net_init ip6_fb_tnl_dev_init(struct net_device *dev)
 	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
 
 	t->parms.proto = IPPROTO_IPV6;
-	dev_hold(dev);
 
 	rcu_assign_pointer(ip6n->tnls_wc[0], t);
 	return 0;
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 3e917e3584596..1ff29eba7df76 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -931,7 +931,6 @@ static int __net_init vti6_fb_tnl_dev_init(struct net_device *dev)
 	struct vti6_net *ip6n = net_generic(net, vti6_net_id);
 
 	t->parms.proto = IPPROTO_IPV6;
-	dev_hold(dev);
 
 	rcu_assign_pointer(ip6n->tnls_wc[0], t);
 	return 0;
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index b1913993b3210..6a5442fdbd516 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1413,7 +1413,6 @@ static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)
 	iph->ihl		= 5;
 	iph->ttl		= 64;
 
-	dev_hold(dev);
 	rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
 }