diff options
| -rw-r--r-- | net/core/net_namespace.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 2213d45fcafd..3c77d84ad60d 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -221,17 +221,26 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id); */ int peernet2id_alloc(struct net *net, struct net *peer) { - bool alloc; + bool alloc = false, alive = false; int id; if (refcount_read(&net->count) == 0) return NETNSA_NSID_NOT_ASSIGNED; spin_lock_bh(&net->nsid_lock); - alloc = refcount_read(&peer->count) == 0 ? false : true; + /* + * When peer is obtained from RCU lists, we may race with + * its cleanup. Check whether it's alive, and this guarantees + * we never hash a peer back to net->netns_ids, after it has + * just been idr_remove()'d from there in cleanup_net(). + */ + if (maybe_get_net(peer)) + alive = alloc = true; id = __peernet2id_alloc(net, peer, &alloc); spin_unlock_bh(&net->nsid_lock); if (alloc && id >= 0) rtnl_net_notifyid(net, RTM_NEWNSID, id); + if (alive) + put_net(peer); return id; } EXPORT_SYMBOL_GPL(peernet2id_alloc); |