FIX: CComQIPtr operator= Causes an Access Violation

 Last reviewed: December 1, 1997
Article ID: Q174891
The information in this article applies to:
  • The Microsoft Active Template Library (ATL), versions 2.0, 2.1

SYMPTOMS

When a CComQIPtr is assigned a NULL pointer, an access violation occurs.

CAUSE

When a CComQIPtr is assigned a NULL pointer, no check is done, and a QueryInterface is attempted with the NULL pointer. This behavior causes the access violation.

RESOLUTION

Do not assign NULL pointer to a CComQIPtr object.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 3.

For more information, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q170365
   TITLE     : INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION

Steps to Reproduce Behavior

   CComQIPtr<IMyInterface, IID_IMyInterface> ptr;
   IUnknown* pUnk = NULL;
   ptr = pUnk;
(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Chuck Bell, Microsoft Corporation 
Keywords          : AtlIss VS97FixlistSP3
Version           : WINDOWS:2.0,2.1
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix kbservicepack

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Last reviewed: December 1, 1997
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