Knowledge Base

FIX: CComQIPtr operator= Causes an Access Violation

Article ID: 174891

Article Last Modified on 10/2/2003

Microsoft ActiveX Template Library 2.0
Microsoft ActiveX Template Library 2.1

This article was previously published under Q174891

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:

170365 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: kbbug kbfix kbvs97sp2fix kbatl300fix kbarchitecture KB174891