4.8-stable review patch. If anyone has any objections, please let me know.
------------------ From: WANG Cong <[email protected]> [ Upstream commit cfc44a4d147ea605d66ccb917cc24467d15ff867 ] Andrei reports we still allocate netns ID from idr after we destroy it in cleanup_net(). cleanup_net(): ... idr_destroy(&net->netns_ids); ... list_for_each_entry_reverse(ops, &pernet_list, list) ops_exit_list(ops, &net_exit_list); -> rollback_registered_many() -> rtmsg_ifinfo_build_skb() -> rtnl_fill_ifinfo() -> peernet2id_alloc() After that point we should not even access net->netns_ids, we should check the death of the current netns as early as we can in peernet2id_alloc(). For net-next we can consider to avoid sending rtmsg totally, it is a good optimization for netns teardown path. Fixes: 0c7aecd4bde4 ("netns: add rtnl cmd to add and get peer netns ids") Reported-by: Andrei Vagin <[email protected]> Cc: Nicolas Dichtel <[email protected]> Signed-off-by: Cong Wang <[email protected]> Acked-by: Andrei Vagin <[email protected]> Signed-off-by: Nicolas Dichtel <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/core/net_namespace.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -217,6 +217,8 @@ int peernet2id_alloc(struct net *net, st bool alloc; int id; + if (atomic_read(&net->count) == 0) + return NETNSA_NSID_NOT_ASSIGNED; spin_lock_irqsave(&net->nsid_lock, flags); alloc = atomic_read(&peer->count) == 0 ? false : true; id = __peernet2id_alloc(net, peer, &alloc);
