Wintrospection plugin attempts to use uninitialized WindowsProcessManager

[LauraLMann]

Work environment

Questions	Answers
System PANDA runs on OS/arch/bits	panda-system-i386
PANDA module affected	wintrospection
Source of PANDA	git clone
Version/git commit	6f3a1c8

Expected behavior

Calling get_current_process_handle osi API function when the current process is 0 returns some kind of dummy value, like maybe 0.

Actual behavior

Segmentation fault because the process object's vmem field is null so it can't be used to get the asid

Steps to reproduce the behavior

Write a little plugin that calls get_current_process_handle and run it on a recording that occasionally has a process 0.

• Use code markdown CODE to make your code visible

When wintrospection notices a task change (via callback or the asid heurestic), it resets the WindowsProcessManager and then, if the current process is not 0, initializes it. But if the current process is 0, the new WindowsProcessManager will not be initialized, so the vmem field in its process object will be 0.
This has been noticed with a Windows 2000 recording (using asid change heuristic) and a Windows XP SP3 recording (using task change callback).

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