[PATCH 4.9 240/240] ipv6: remove extra dev_hold() for fallback tunnels

Greg Kroah-Hartman
2021-05-20T11:25:14Z

From: Eric Dumazet <edumazet@google.com>

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>
---
net/ipv6/ip6_gre.c | 3 ---
net/ipv6/ip6_tunnel.c | 1 -
net/ipv6/ip6_vti.c | 1 -
net/ipv6/sit.c | 1 -
4 files changed, 6 deletions(-)

--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -350,7 +350,6 @@ static struct ip6_tnl *ip6gre_tunnel_loc
if (!(nt->parms.o_flags & TUNNEL_SEQ))
dev->features |= NETIF_F_LLTX;

- dev_hold(dev);
ip6gre_tunnel_link(ign, nt);
return nt;

@@ -1085,8 +1084,6 @@ static void ip6gre_fb_tunnel_init(struct
strcpy(tunnel->parms.name, dev->name);

tunnel->hlen = sizeof(struct ipv6hdr) + 4;
-
- dev_hold(dev);
}

--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1888,7 +1888,6 @@ static int __net_init ip6_fb_tnl_dev_ini
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;
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -945,7 +945,6 @@ static int __net_init vti6_fb_tnl_dev_in
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;
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1414,7 +1414,6 @@ static void __net_init ipip6_fb_tunnel_i
iph->ihl = 5;
iph->ttl = 64;

- dev_hold(dev);
rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
}