@@ -224,16 +224,25 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id);
*/
int peernet2id_alloc(struct net *net, struct net *peer)
{
+ bool alloc = false, alive = false;
unsigned long flags;
- bool alloc;
int id;
spin_lock_irqsave(&net->nsid_lock, flags);
- alloc = atomic_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_irqrestore(&net->nsid_lock, flags);
if (alloc && id >= 0)
rtnl_net_notifyid(net, RTM_NEWNSID, id);
+ if (alive)
+ put_net(peer);
return id;
}
EXPORT_SYMBOL_GPL(peernet2id_alloc);