WOW Applications Stack Fault When Launched by a Service

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0

SYMPTOMS

Windows on Windows (WOW), or 16-bit Windows applications, may terminate with a stack fault error when launched by a Windows NT service. The stack fault error will look similar to the following:

   Application Error caused a stack fault in module UNKNOWN at address
   00c7:4394f Will Close.

CAUSE

WOW applications create a secure shared memory region during startup that allows only logged on users access. When a service launches a second WOW application, the resulting process will attempt to open the existing shared memory region. Because the security context of the process started by a service is not purely interactive, when it attempts to access the existing shared memory region, it gets an access denied error. The second WOW process will continually try to access the existing shared memory region until a stack fault occurs and it terminates.

RESOLUTION

Wow32.dll and Vdmdbg.dll were modified to allow non-logged on users access to the shared memory region.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K