SMS: Remote Control to Windows 9x Clients Fails with Winsock 2.0, Using IP

ID: Q193269

The information in this article applies to:

Microsoft Systems Management Server version 1.2

SYMPTOMS

When attempting to Remote Control a Windows 95 or Windows 98 client using Winsock2 and having IP as the default protocol, Remote Control will fail. The client will experience a general protection (GP) fault in Idisp16.dll.

CAUSE

In versions earlier than Winsock 2.0, WUSER (actually Idisp16.dll) is able to call Winsock from the 16-bit display driver code and the packets are sent without executing any 32-bit code. In Winsock 2.0, the work is done in 32-bit code. If the display driver wants to send a packet, its Winsock call is called through a thunk to the 32-bit code. Calling through the thunk releases the "Win16 Mutex," which allows multiple threads to enter the Graphics Device Interface (GDI) and USER at the same time. The results can include problems at the viewer (scrambled screens or program halts), and even screen corruption on the client.

Windows 95 or Windows 98 with Winsock 1.1 (that is, the release version of Windows 95, or Windows 98 with Winsock 2.0 support removed) has the following architecture as interpreted by 16-bit applications and DLLs:


  16-bit application or DLL
         |
   Winsock.dll    (16-bit winsock interface, pure 16-bit code)
         |           user
   ------------------------
         |           kernel
   Wsock.vxd

In Windows 95 or Windows 98 with Winsock 2.0 (with only Microsoft TCP/IP provider installed, the shipping configuration) it has changed to the following:


16-bit application or DLL
         |
   Winsock.dll    (16-bit winsock interface, pure 16-bit code)
         |
   Ws2thl.dll     (thunking layer between 16-bit and 32-bit code)
         |
   Ws2_32.dll     (Winsock2 broker library, 32-bit code)
         |
   Msafd.dll      (TCP/IP service provider, 32-bit code)
         |              user
   ---------------------------
         |              kernel
   Wsock2.vxd

Wuser.exe (Idisp16.dll) is a 16-bit DLL being called inside a 32-bit process. It makes 16-bit Winsock calls and relies on the Winsock 1.1 behavior of going straight to kernel without thunking into 32-bit code. With Winsock 2.0, when Winsock.dll thunks to 32-bit code, the 32-bit scheduler can (and very often does) preempt a currently executing thread and then executes another 32-bit thread in the same or different 32-bit process. When this occurs, the 16-bit DLL code can get reentered and halt the program, because a 16-bit environment assumes that no reentrancy will occur when it makes a Winsock call.

RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Systems Management Server service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

The English version of this fix should have the following file attributes or later:


   Date        Time     Version         Size     File name    Platform
   -------------------------------------------------------------------
    4/14/99   6:24pm                  202,476   Cli_Dos.exe   x86
   12/18/98   1:12am                   12,288  CoExst9x.dll   x86
    4/22/99   5:05pm                   98,777   IDisp9x.dll   x86
    4/22/99   5:05pm 2.00.1239.0029     8,464  IDispThk.dll   x86
    4/22/99   5:05pm 2.00.1239.0029    46,512     Imp9x.dll   x86
   12/18/98   1:12am                   75,968  Loc16VC0.dll   x86 
    4/22/99   5:05pm 2.00.1239.0014    84,112  MultPr9x.dll   x86
    4/22/99   5:05pm 2.00.1239.0029    38,320   Queue9x.dll   x86
    4/22/99   1:22pm                    8,024   VUser9x.vxd   x86
    4/22/99   5:05pm 2.00.1239.0029    27,424  WouDat9x.dll   x86
    4/22/99   1:21pm 2.00.1239.0029   287,744   Wuser9x.exe   x86
    4/28/99   1:50pm                    3,525    CL_W95.mod   x86
    4/22/99   5:06pm 2.00.1239.0029    36,800   WUMsg9x.dll   x86
    4/22/99   5:05pm 2.00.1239.0029     4,720  _IDisp9x.dll   x86
    4/22/99   5:05pm 2.00.1239.0029    91,584  _Wuser9x.dll   x86
    4/27/99   5:54pm                    2,451    System.ma_
     5/3/99   3:01pm                  935,197   Hf33216.exe

NOTE: Due to file dependencies, the most recent hotfix or feature that contains the above files may also contain additional files.

WORKAROUND

To work around this problem, use either NetBIOS or IPX as the default protocol for Systems Management Server Remote Control.

STATUS

Microsoft has confirmed this to be a problem in Systems Management Server version 1.2.

MORE INFORMATION

Before applying this hotfix, back up the entire Systems Management Server site server.

NOTE: This hotfix requires Systems Management Server 1.2 Service Pack 4 to be installed before the hotfix can be applied.

To install the hotfix using the installation program provided, do the following at the Systems Management Server site server:

Run the HF33216.exe file.

This Systems Management Server Installer package will install the following new files in your Systems Management Server site server's SMS_root\Site.srv\Maincfg.box\Client.src\X86.bin directory:


       Cli_dos.exe
      CoExst9x.dll
       IDisp9x.dll
      IDispThk.dll
         Imp9x.dll
      Loc16VC0.dll
      MultPr9x.dll
       Queue9x.dll
       VUser9x.vxd
      WouDat9x.dll
       Wuser9x.exe

This package will then install the following new files in your Systems Management Server site server's SMS_root\Site.srv\Maincfg.box\Client.src\X86.bin\00000409 directory:
```
        CL_W95.mod
       WUMsg9x.dll
      _IDisp9x.dll
      _Wuser9x.dll 
```

This package will then modify the System.map file to support the installation of these new files to the Windows 95 and Windows 98 clients.

After the Systems Management Server services are restarted, the files will be replicated by Maintenance Manger to all Systems Management Server logon servers to the SMS\Logon.srv\X86.bin directory. When that occurs, the clients can be updated.

To update the clients, either manually run Upgrade.bat on each client or follow the instructions in the following article in the Microsoft Knowledge Base:

Q166771 SMS: How to Force Site-Wide Client Updates

To install the hotfix manually, perform the steps below at the Systems Management Server site server.
WARNING: This method involves making changes to the System.map file. Editing the System.map file incorrectly can damage your site installation, and should only be done according to this specific procedure or at the direction of Systems Management Server Support.

Stop the SMS_EXECUTIVE, SMS_SITE_CONFIG_MANAGER, and SMS_HIERARCHY_MANAGER services.

Copy the following files into the SMS_root\Site.srv\Maincfg.box\Client.src\X86.bin directory:


       Cli_dos.exe
      CoExst9x.dll
       IDisp9x.dll
      IDispThk.dll
         Imp9x.dll
      Loc16VC0.dll
      MultPr9x.dll
       Queue9x.dll
       VUser9x.vxd
      WouDat9x.dll
       Wuser9x.exe

Copy the following files into the SMS_root\Site.srv\Maincfg.box\Client.src\X86.bin\00000409 directory:
```
        CL_W95.mod
       WUMsg9x.dll
      _IDisp9x.dll
      _Wuser9x.dll 
```

Make a backup copy of the current System.map file.

Remove 16-bit WUSER support for Windows 95 and Windows 98. To do this, search the System.map file, and look for the Wuser.exe entry in the section titled:
```
DIRECTORY "SITE.SRV\MAINCFG.BOX\CLIENT.SRC\X86.BIN"
   PLATFORM "INTEL X86" LANGUAGE "" SOURCE "X86\INTNL" FLAGS = 10
   UNIT = "INTEL CLIENT" 
```

Remove Wuser.exe from the WIN95 CopyList. To do this, look under the line for Wuser.exe; the following line needs to be changed from:


REMOTE=YES,   COPYLISTS("WIN16:REMOTE_CONTROL" = "SMS", "WIN95:REMOTE_CONTROL" = "SMS"), COMPRESS=NO, FLAGS = 5

To:


REMOTE=YES,   COPYLISTS("WIN16:REMOTE_CONTROL" = "SMS"), COMPRESS=NO, FLAGS = 5

Remove Vuser.386 from the WIN95 CopyList. To do this, look under the line for Vuser.386; the following line needs to be changed from:


    REMOTE=YES,   COPYLISTS("WIN16:REMOTE_CONTROL_386" = "WINDIR", "WIN95:REMOTE_CONTROL_386" = "WINDIR"), COMPRESS=NO, FLAGS = 1

To:


    REMOTE=YES,   COPYLISTS("WIN16:REMOTE_CONTROL_386" = "WINDIR"), COMPRESS=NO, FLAGS = 1

Search the System.map file looking for the _Wuser.dll entry in the section titled:


DIRECTORY "SITE.SRV\MAINCFG.BOX\CLIENT.SRC\X86.BIN\00000409"
   PLATFORM "INTEL X86" LANGUAGE "ENGLISH" SOURCE "X86\ENGLISH" FLAGS = 10
UNIT = "INTEL CLIENT"

Remove _Wuser.dll from the WIN95 CopyList. To do this, look under the line for _Wuser.dll; the following line needs to be changed from:


REMOTE=YES,   COPYLISTS("WIN16:REMOTE_CONTROL" = "SMS", "WIN95:REMOTE_CONTROL" = "SMS"), COMPRESS=NO, FLAGS = 5

To:


REMOTE=YES,   COPYLISTS("WIN16:REMOTE_CONTROL" = "SMS"), COMPRESS=NO, FLAGS = 5

Merge the new additions that are located in the enclosed System.ma_ file. The headers for each section in the System.ma_ file are included for reference, but you only need to merge the new lines into the appropriate matching section in the System.map file. Please pay attention to these headers because some do look similar but are definitely not the same. HINT: Look for Wuser.exe in a X86 platform, and Wusermsg.dll for the same platform, and then merge into those areas.

Restart the SMS_EXECUTIVE, SMS_SITE_CONFIG_MANAGER, and SMS_HIERARCHY_MANAGER services.

Wait for the copylist files to be upgraded from the System.map and the new files to be replicated by Maintenance Manager to the SMS\Logon.srv\X86.bin directory on all Systems Management Server logon servers. When that occurs, the clients can be updated.

To update the clients, either manually run Upgrade.bat on each client or follow the instructions in the following article in the Microsoft Knowledge Base:

Q166771 SMS: How to Force Site-Wide Client Updates

Additional query words: prodsms RemoteHelp HelpDesk GPF winsock2 RC

Keywords : kbSMS120 kbSMS120bug smsremtshoot kbbug1.20
Version : winnt:1.2
Platform : winnt
Issue type : kbbug