REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1935
Before use the memory that is allocated through AllocateZeroPool,
we should check the memory pointer is valid to avoid using the
NULL pointer.
Add check for VariableArrayAddress that is returned from
GetScatterGatherHeadEntries. If it is NULL, directly return
the error status.
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Signed-off-by: Zhichao Gao <zhichao.gao@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>