This is a note to let you know that I've just added the patch titled ipv6: remove extra dev_hold() for fallback tunnels to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ipv6-remove-extra-dev_hold-for-fallback-tunnels.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 0d7a7b2014b1a499a0fe24c9f3063d7856b5aaaf Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Wed, 31 Mar 2021 14:38:11 -0700 Subject: ipv6: remove extra dev_hold() for fallback tunnels From: Eric Dumazet <edumazet@xxxxxxxxxx> 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@xxxxxxxxxx> Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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; @@ -1124,8 +1123,6 @@ 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 @@ -1905,7 +1905,6 @@ 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 @@ -934,7 +934,6 @@ 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 @@ -1407,7 +1407,6 @@ 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); } Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are queue-4.14/ip6_tunnel-sit-proper-dev_-hold-put-in-ndo_init-methods.patch queue-4.14/sit-proper-dev_-hold-put-in-ndo_init-methods.patch queue-4.14/ip6_vti-proper-dev_-hold-put-in-ndo_-un-init-methods.patch queue-4.14/netfilter-nftables-avoid-overflows-in-nft_hash_bucke.patch queue-4.14/ipv6-remove-extra-dev_hold-for-fallback-tunnels.patch