Add NULL pointer check before using a pointer to avoid possible NULL pointer dereference. Cc: Eric Dong <eric.dong@intel.com> Cc: Hao Wu <hao.a.wu@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Dandan Bi <dandan.bi@intel.com> Reviewed-by: Hao Wu <hao.a.wu@intel.com>