AttributeError: 'NoneType' object has no attribute 'decode'

[dhondta]

I experienced the following bug using your plugin:

$ volatility editbox -f [...] --profile=[...] -p [...] --dump-dir [...]
Volatility Foundation Volatility Framework 2.6
******************************
[...]
Traceback (most recent call last):
  File "/usr/bin/volatility", line 192, in <module>
    main()
  File "/usr/bin/volatility", line 183, in main
    command.execute()
  File "/usr/local/lib/python2.7/dist-packages/volatility-2.6-py2.7.egg/volatility/commands.py", line 147, in execute
    func(outfd, data)
  File "/usr/local/lib/python2.7/dist-packages/volatility-2.6-py2.7.egg/volatility/plugins/gui/editbox.py", line 462, in render_text
    ctrl.dump_meta(outfd)
  File "/usr/local/lib/python2.7/dist-packages/volatility-2.6-py2.7.egg/volatility/plugins/gui/editbox.py", line 224, in dump_meta
    outfd.write('undoBuf           : {}\n'.format(self.get_undo(no_crlf=True)))
  File "/usr/local/lib/python2.7/dist-packages/volatility-2.6-py2.7.egg/volatility/plugins/gui/editbox.py", line 200, in get_undo
    return self.obj_vm.read(self.undoBuf, self.undoLen * 2).decode('utf-16').replace('\r\n', '.')
AttributeError: 'NoneType' object has no attribute 'decode'

Offending lines: 199 to 202

if no_crlf:
    return self.obj_vm.read(self.undoBuf, self.undoLen * 2).decode('utf-16').replace('\r\n', '.')
else:
    return self.obj_vm.read(self.undoBuf, self.undoLen * 2).decode('utf-16')

It seems that, in some cases, self.obj_vm.read(self.undoBuf, self.undoLen * 2) is None and therefore causes the error while the plugin could complete.

Proposed fix:

r = self.obj_vm.read(self.undoBuf, self.undoLen * 2)
if r is not None:
    r = r.decode('utf-16')
    return r.replace('\r\n', '.') if no_crlf else r