BaseTools: Fix Section header size larger than elf file size bug

Add the logic to handle the case that Section header size larger than
elf file size.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yunhua Feng <yunhuax.feng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/C/GenFw/Elf64Convert.c

@@ -670,6 +670,9 @@ WriteSections64 (
       switch (Shdr->sh_type) {
       case SHT_PROGBITS:
         /* Copy.  */
+        if (Shdr->sh_offset + Shdr->sh_size > mFileBufferSize) {
+          return FALSE;
+        }
         memcpy(mCoffFile + mCoffSectionsOffset[Idx],
               (UINT8*)mEhdr + Shdr->sh_offset,
               (size_t) Shdr->sh_size);