layers: Fix up uses of is_valid.

volatility/framework/plugins/windows/callbacks.py

@@ -185,9 +185,7 @@ class Callbacks(interfaces.plugins.PluginInterface):
                                          layer_name = layer_name)
 
         for callback in callback_record.Entry:
-            try:
-                context.layers[layer_name].is_valid(callback.CallbackRoutine)
-            except exceptions.InvalidAddressException:
+            if not context.layers[layer_name].is_valid(callback.CallbackRoutine, 64):
                 continue
 
             try:
@@ -228,9 +226,7 @@ class Callbacks(interfaces.plugins.PluginInterface):
 
         for callback in callback_record.Entry:
 
-            try:
-                context.layers[layer_name].is_valid(callback.CallbackRoutine)
-            except exceptions.InvalidAddressException:
+            if not context.layers[layer_name].is_valid(callback.CallbackRoutine, 64):
                 continue
 
             try:

volatility/framework/plugins/windows/handles.py

@@ -298,7 +298,6 @@ class Handles(interfaces.plugins.PluginInterface):
 
             for entry in self.handles(object_table):
                 try:
-                    self.context.layers[self.config["primary"]].is_valid(entry.vol.offset)
                     obj_type = entry.get_object_type(type_map, cookie)
                     if obj_type is None:
                         continue

volatility/framework/plugins/windows/malfind.py

@@ -55,7 +55,7 @@ class Malfind(interfaces.plugins.PluginInterface):
 
         while offset < vad_length:
             next_addr = vad.get_start() + offset
-            if proc_layer.is_valid(next_addr) and proc_layer.read(next_addr, CHUNK_SIZE) != all_zero_page:
+            if proc_layer.is_valid(next_addr, CHUNK_SIZE) and proc_layer.read(next_addr, CHUNK_SIZE) != all_zero_page:
                 return False
             offset += CHUNK_SIZE