[PATCH] Fix ipc entries removal

Fix two issuses related to ipc_ids->entries freeing.

1. When freeing ipc namespace we need to free entries allocated
   with ipc_init_ids().

2. When removing old entries in grow_ary() ipc_rcu_putref()
   may be called on entries set to &ids->nullentry earlier in
   ipc_init_ids().
   This is almost impossible without namespaces, but with
   them this situation becomes possible.

Found during OpenVZ testing after obvious leaks in beancounters.
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Cc: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

ipc/msg.c

@@ -124,6 +124,7 @@ void msg_exit_ns(struct ipc_namespace *ns)
 	}
 	mutex_unlock(&msg_ids(ns).mutex);
 
+	ipc_fini_ids(ns->ids[IPC_MSG_IDS]);
 	kfree(ns->ids[IPC_MSG_IDS]);
 	ns->ids[IPC_MSG_IDS] = NULL;
 }

ipc/sem.c

@@ -161,6 +161,7 @@ void sem_exit_ns(struct ipc_namespace *ns)
 	}
 	mutex_unlock(&sem_ids(ns).mutex);
 
+	ipc_fini_ids(ns->ids[IPC_SEM_IDS]);
 	kfree(ns->ids[IPC_SEM_IDS]);
 	ns->ids[IPC_SEM_IDS] = NULL;
 }

ipc/shm.c

@@ -116,6 +116,7 @@ void shm_exit_ns(struct ipc_namespace *ns)
 	}
 	mutex_unlock(&shm_ids(ns).mutex);
 
+	ipc_fini_ids(ns->ids[IPC_SHM_IDS]);
 	kfree(ns->ids[IPC_SHM_IDS]);
 	ns->ids[IPC_SHM_IDS] = NULL;
 }

ipc/util.c

@@ -301,7 +301,7 @@ static int grow_ary(struct ipc_ids* ids, int newsize)
 	 */
 	rcu_assign_pointer(ids->entries, new);
 
-	ipc_rcu_putref(old);
+	__ipc_fini_ids(ids, old);
 	return newsize;
 }
 

ipc/util.h

@@ -83,6 +83,18 @@ void* ipc_rcu_alloc(int size);
 void ipc_rcu_getref(void *ptr);
 void ipc_rcu_putref(void *ptr);
 
+static inline void __ipc_fini_ids(struct ipc_ids *ids,
+		struct ipc_id_ary *entries)
+{
+	if (entries != &ids->nullentry)
+		ipc_rcu_putref(entries);
+}
+
+static inline void ipc_fini_ids(struct ipc_ids *ids)
+{
+	__ipc_fini_ids(ids, ids->entries);
+}
+
 struct kern_ipc_perm* ipc_get(struct ipc_ids* ids, int id);
 struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id);
 void ipc_lock_by_ptr(struct kern_ipc_perm *ipcp);