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Q111591: BUG: IsBadStringPtr() Reports Bad String as Valid

Article: Q111591
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1
Operating System(s): 
Keyword(s): 
Last Modified: 06-NOV-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) 3.1 
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SYMPTOMS
========

Under a particular condition, IsBadStringPtr() will report that a bad string is
valid. If the pointer passed to IsBadStringPtr() refers to a block of memory of
size 0xFFFF and is filled with all nonzero data, IsBadStringPtr() returns 0.

STATUS
======

Microsoft has confirmed this to be a bug in Windows version 3.1. We are
researching this problem and will post new information here in the Microsoft
Knowledge Base as it becomes available.

MORE INFORMATION
================

For IsBadStringPtr() to validate a string, it must be passed a pointer to valid
memory and the string must contain a NULL character that terminates the string.

The following code illustrates the error:

  #include <windows.h>
  #include <windowsx.h>
  #include <memory.h>

  LPSTR lpPtr;
  BOOL fRet;

       // GlobalAllocPtr is a macro in WINDOWSX.H
  lpPtr = GlobalAllocPtr(GMEM_MOVEABLE, 0XFFFF);

  _fmemset(lpPtr, 'Q', 0xFFFF);

  Ret = IsBadStringPtr(lpPtr, 0xFFFF);

  if (fRet)  // ... etcetera, fRet incorrectly contains zero.

Additional query words: buglist3.10 3.10

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1

=============================================================================

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