From cfc44a4d147ea605d66ccb917cc24467d15ff867 Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Wed, 16 Nov 2016 10:27:02 -0800 Subject: [PATCH] net: check dead netns for peernet2id_alloc() 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 Cc: Nicolas Dichtel Signed-off-by: Cong Wang Acked-by: Andrei Vagin Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller --- net/core/net_namespace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index f61c0e02a413..7001da910c6b 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -219,6 +219,8 @@ int peernet2id_alloc(struct net *net, struct net *peer) 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); -- 2.30.2