[Bug 49414] New: DefWindowProcW doesn't handle WIN_GetPtr properly when handling WM_GETTEXTLENGTH

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=49414

Bug ID: 49414
           Summary: DefWindowProcW doesn't handle WIN_GetPtr properly when
                    handling WM_GETTEXTLENGTH
           Product: Wine
           Version: unspecified
          Hardware: x86
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: user32
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

case WM_GETTEXTLENGTH:
        {
            WND *wndPtr = WIN_GetPtr( hwnd );
            if (wndPtr && wndPtr->text) result =
(LRESULT)strlenW(wndPtr->text);
            WIN_ReleasePtr( wndPtr );
        }
        break;

(from dlls/user32/defwnd.c:998)

WIN_GetPtr can return WND_OTHER_PROCESS, which this code does not check for
(for example, dlls/user32/defwnd.c:550 checks for it properly). A lot of other
code in defwnd.c doesn't check for it, so it looks like having a window be
valid for another process could cause problems.