4.4-stable review patch. If anyone has any objections, please let me know.
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From: WANG Cong xiyou.wangcong@gmail.com
commit 76da0704507bbc51875013f6557877ab308cfd0a upstream.
In commit 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf") I assumed NETDEV_REGISTER and NETDEV_UNREGISTER are paired, unfortunately, as reported by jeffy, netdev_wait_allrefs() could rebroadcast NETDEV_UNREGISTER event until all refs are gone.
We have to add an additional check to avoid this corner case. For netdev_wait_allrefs() dev->reg_state is NETREG_UNREGISTERED, for dev_change_net_namespace(), dev->reg_state is NETREG_REGISTERED. So check for dev->reg_state != NETREG_UNREGISTERED.
Fixes: 242d3a49a2a1 ("ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf") Reported-by: jeffy jeffy.chen@rock-chips.com Cc: David Ahern dsahern@gmail.com Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Acked-by: David Ahern dsahern@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Cc: Konstantin Khlebnikov khlebnikov@yandex-team.ru Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/ipv6/route.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -3378,7 +3378,11 @@ static int ip6_route_dev_notify(struct n net->ipv6.ip6_blk_hole_entry->dst.dev = dev; net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev); #endif - } else if (event == NETDEV_UNREGISTER) { + } else if (event == NETDEV_UNREGISTER && + dev->reg_state != NETREG_UNREGISTERED) { + /* NETDEV_UNREGISTER could be fired for multiple times by + * netdev_wait_allrefs(). Make sure we only call this once. + */ in6_dev_put(net->ipv6.ip6_null_entry->rt6i_idev); #ifdef CONFIG_IPV6_MULTIPLE_TABLES in6_dev_put(net->ipv6.ip6_prohibit_entry->rt6i_idev);