StandaloneMmPkg/Core: Fix issue that offset calculation might be wrong

MmCoreFfsFindMmDriver() assumes FileHeader is EFI_FFS_FILE_HEADER.
If FileHeader is an EFI_FFS_FILE_HEADER2, 'FileHeader + 1' will get a
wrong section address. Use FfsFindSection to get the section directly,
instead of 'FileHeader + 1' to avoid this issue.
MmCoreFfsFindMmDriver() also assumes section is EFI_COMMON_SECTION_HEADER.
If Section is EFI_COMMON_SECTION_HEADER2, 'Section + 1' will get a wrong
wrong InnerFvHeader adress. Add section head detection and calculate the
address accordingly.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Wei6 Xu <wei6.xu@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

StandaloneMmPkg/Core/FwVol.c

@@ -79,8 +79,6 @@ MmCoreFfsFindMmDriver (
   UINTN                       DepexSize;
   UINTN                       Index;
   EFI_COMMON_SECTION_HEADER   *Section;
-  VOID                        *SectionData;
-  UINTN                       SectionDataSize;
   UINT32                      DstBufferSize;
   VOID                        *ScratchBuffer;
   UINT32                      ScratchBufferSize;
@@ -117,23 +115,21 @@ MmCoreFfsFindMmDriver (
       break;
     }
 
-    Status = FfsFindSectionData (
+    Status = FfsFindSection (
                EFI_SECTION_GUID_DEFINED,
                FileHeader,
-               &SectionData,
-               &SectionDataSize
+               &Section
                );
     if (EFI_ERROR (Status)) {
       break;
     }
 
-    Section = (EFI_COMMON_SECTION_HEADER *)(FileHeader + 1);
-    Status  = ExtractGuidedSectionGetInfo (
-                Section,
-                &DstBufferSize,
-                &ScratchBufferSize,
-                &SectionAttribute
-                );
+    Status = ExtractGuidedSectionGetInfo (
+               Section,
+               &DstBufferSize,
+               &ScratchBufferSize,
+               &SectionAttribute
+               );
     if (EFI_ERROR (Status)) {
       break;
     }
@@ -194,8 +190,13 @@ MmCoreFfsFindMmDriver (
       goto FreeDstBuffer;
     }
 
-    InnerFvHeader = (VOID *)(Section + 1);
-    Status        = MmCoreFfsFindMmDriver (InnerFvHeader, Depth + 1);
+    if (IS_SECTION2 (Section)) {
+      InnerFvHeader = (VOID *)((EFI_COMMON_SECTION_HEADER2 *)Section + 1);
+    } else {
+      InnerFvHeader = (VOID *)(Section + 1);
+    }
+
+    Status = MmCoreFfsFindMmDriver (InnerFvHeader, Depth + 1);
     if (EFI_ERROR (Status)) {
       goto FreeDstBuffer;
     }