Re: CredUIPromptForCredentials and Stack Overflow under Debugger???

From:
Jeffrey Walton <noloader@gmail.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Sun, 21 Jun 2009 00:31:52 -0700 (PDT)
Message-ID:
<fa6cd24b-dcff-421d-b83c-503f9eb76124@j12g2000vbl.googlegroups.com>
Found it (Release would have probably broken, but in an intermittent
manner). szUsername and szPassword is an In/Out parameter. So the
following change was made. I should have paid better attention to
Howard and LeBlac.

 WCHAR szUsername[CREDUI_MAX_USERNAME_LENGTH+1];
 WCHAR szPassword[CREDUI_MAX_PASSWORD_LENGTH+1];

 // In/Out parameters
 ZeroMemory( szUsername, sizeof(szUsername));
 ZeroMemory( szPassword, sizeof(szPassword));

On Jun 21, 12:40 am, Jeffrey Walton <noloa...@gmail.com> wrote:

Hi All,

XP Pro fully patched, Visual Studio 2005, 6.1 SDK, MFC Dialog
application

CredUIPromptForCredentials is giving me troubles. It appears to happen
only under the debugger (release is OK). Unfortunately, I still need
the debugger. I seem to have a recursive call with the following co-
conspirators:

* _AfxActivationWndProc
* _CallWindowProc
* _InternalCallWinProc
* CreduiPasswordDialog::CmdLineMessageHandler
* CreduiPasswordDialog::CmdLineMessageHandlerCallback
* _SendMessageWorker
* _DefWindowProc
* _RealWindowProc
* _UserCallWindowProcCheck
* _InternalCallWinProc
**** Repeat ****

I've got to admit that I *do not* understand why a command line
function is called. Is this by design?

The code that follows is nearly identical to Howard and LeBlac's
Writing Secure Code. I've also tried setting credinfo.hwndParent to
CWnd::GetSafeHwnd().

Jeff

CREDUI_INFO credinfo;
ZeroMemory( &credinfo, sizeof(credinfo) );

credinfo.cbSize = sizeof(credinfo);
credinfo.hwndParent = NULL;
credinfo.pszCaptionText = L"Alternate Credentials";
credinfo.pszMessageText = L"Please enter the alternate credentials";

WCHAR szUsername[CREDUI_MAX_USERNAME_LENGTH+1];
WCHAR szPassword[CREDUI_MAX_PASSWORD_LENGTH+1];

__try {

        PCWSTR pszTarget = L"Server";
        DWORD dwReason = 0;
        BOOL bSave = FALSE;
        DWORD dwFlags = CREDUI_FLAGS_ALWAYS_SHOW_UI |
            CREDUI_FLAGS_GENERIC_CREDENTIALS;

        DWORD dwReturn = CredUIPromptForCredentials(
            &credinfo, pszTarget, NULL,
            dwReason,
            szUsername, _countof(szUsername),
            szPassword, _countof(szPassword),
            &bSave, dwFlags );

        if( ERROR_SUCCESS != dwReturn ) {
                MessageBox( L"Failed to acquire alternate=

 user

credentials",
                    NULL, MB_ICONERROR );
                return;
        }

        // Use username and password
       ...}

__finally {
        SecureZeroMemory( szUsername, sizeof(szUsername));
        SecureZeroMemory( szPassword, sizeof(szPassword));

}

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