Functions may leak memory if an exception is thrown by the COM object when you use #import to generate wrapper classes for COM objects

When using #import to generate wrapper classes for COM objects, _com_dispatch_method(), _com_dispatch_raw_method(), _com_dispatch_propput(), _com_dispatch_raw_propput(), _com_dispatch_propget(), and _com_dispatch_raw_propget() function calls may be generated.

These functions leak memory if an exception is thrown by the COM object. Specifically, ICreateErrorInfo is not released and three BSTRs are not freed.

This is due to a bug in the internal implementation of the compiler native COM support.

A supported fix that corrects this problem is now available from Microsoft.

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://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

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

Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section.

For more information about Visual Studio service packs, click the following article number to view the article in the Microsoft Knowledge Base:

Steps to reproduce behavior

1. Create a Visual Basic COM server. You can choose ActiveX DLL.
2. Name the project LeakServer.
3. Name the class LeakTester.
4. Add one Public Sub called Leak to the class. For example:

          Public Sub Leak()
   
          End Sub
   					

5. Add the following code to the Leak Subroutine:

            Err.Raise vbObjectError + &H200 + 5
   					

6. Build the ActiveX DLL. When prompted, place the DLL on C drive.
7. Create a new MFC AppWizard-generated dialog box application. Name it LeakTest.
8. Add the following line to the Stdafx.h file:

        #import "C:\LeakServer.dll" no_namespace no_dual_interfaces
   					

9. Add a button and use Class Wizard to add a BN_CLICK handler.
10. Add the following code to the handler:

      _LeakTesterPtr serv;
      HRESULT hr = serv.CreateInstance(__uuidof(LeakTester));
      if (FAILED(hr))
      {
          TRACE("Create failed= %x\n", hr);
          return;
      }
    
      int nResponse = AfxMessageBox ("Catch 10 _com_errors?", MB_YESNO);
      while (IDYES == nResponse)
      {
         for (int iLoop = 0; iLoop < 10; iLoop++)
         {
            try
            {
              serv->Leak();
            }
            catch(_com_error &x)
            {
              int i = 0;
            }
        }
        nResponse = AfxMessageBox ("Catch 10 _com_errors?", MB_YESNO);
      }
    
    					

11. Add the following code before the button handler:

    struct InitCOM
    {
      InitCOM()  { CoInitialize(NULL); }
      ~InitCOM() { CoUninitialize();   }
    } g_Init;
    					

12. Build and test.

You can use Task Manager in Windows NT to see the memory increase through each iteration.