Improve security when using cPickle

tryton/pysocket.py

@@ -1,5 +1,6 @@
 import socket
 import cPickle
+import cStringIO
 
 DNS_CACHE = {}
 
@@ -83,7 +84,10 @@ class PySocket:
             if chunk == '':
                 raise RuntimeError, "socket connection broken"
             msg = msg + chunk
-        res = cPickle.loads(msg)
+        msgio = cStringIO.StringIO(msg)
+        unpickler = cPickle.Unpickler(msgio)
+        unpickler.find_global = None
+        res = unpickler.load()
         if isinstance(res[0], Exception):
             if exception:
                 raise PySocketException(str(res[0]), str(res[1]))