win32u: Reject invalid length in SetWindowPlacement.

dlls/user32/tests/win.c

@@ -12504,10 +12504,8 @@ static void test_window_placement(void)
     wp.length = 0;
     SetLastError(0xdeadbeef);
     ret = SetWindowPlacement(hwnd, &wp);
-todo_wine {
     ok(!ret, "SetWindowPlacement should have failed\n");
     ok(GetLastError() == ERROR_INVALID_PARAMETER, "wrong error %lu\n", GetLastError());
-}
 
     DestroyWindow(hwnd);
 }

dlls/win32u/window.c

@@ -2567,6 +2567,11 @@ BOOL WINAPI NtUserSetWindowPlacement( HWND hwnd, const WINDOWPLACEMENT *wpl )
 {
     UINT flags = PLACE_MAX | PLACE_RECT;
     if (!wpl) return FALSE;
+    if (wpl->length != sizeof(*wpl))
+    {
+        RtlSetLastWin32Error( ERROR_INVALID_PARAMETER );
+        return FALSE;
+    }
     if (wpl->flags & WPF_SETMINPOSITION) flags |= PLACE_MIN;
     return set_window_placement( hwnd, wpl, flags );
 }