[PATCH v2 4/6] MdeModulePkg: SmiHandlerProfileInfo: Updated MessageLength calculation

["Kun Qin" <kuqin12@gmail.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3398

This change replaced the calculation of communication buffer size from
explicitly adding the size of each member with the OFFSET macro function.
This will make the structure field defition change transparent to
consumers.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>

Signed-off-by: Kun Qin <kuqin12@gmail.com>
---

Notes:
    v2:
    - Updated comments by removing "BZ" tags [Hao]

 MdeModulePkg/Application/SmiHandlerProfileInfo/SmiHandlerProfileInfo.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Application/SmiHandlerProfileInfo/SmiHandlerProfileInfo.c b/MdeModulePkg/Application/SmiHandlerProfileInfo/SmiHandlerProfileInfo.c
index 4153074b7a80..4bfd5946caba 100644
--- a/MdeModulePkg/Application/SmiHandlerProfileInfo/SmiHandlerProfileInfo.c
+++ b/MdeModulePkg/Application/SmiHandlerProfileInfo/SmiHandlerProfileInfo.c
@@ -116,7 +116,10 @@ GetSmiHandlerProfileDatabase(
   CommGetInfo->Header.ReturnStatus = (UINT64)-1;
   CommGetInfo->DataSize = 0;
 
-  CommSize = sizeof(EFI_GUID) + sizeof(UINTN) + CommHeader->MessageLength;
+  //
+  // The CommHeader->MessageLength contains a definitive value, thus UINTN cast is safe here.
+  //
+  CommSize = OFFSET_OF(EFI_SMM_COMMUNICATE_HEADER, Data) + (UINTN)CommHeader->MessageLength;
   Status = SmmCommunication->Communicate(SmmCommunication, CommBuffer, &CommSize);
   if (EFI_ERROR(Status)) {
     Print(L"SmiHandlerProfile: SmmCommunication - %r\n", Status);
@@ -149,7 +152,10 @@ GetSmiHandlerProfileDatabase(
   CommGetData->Header.DataLength = sizeof(*CommGetData);
   CommGetData->Header.ReturnStatus = (UINT64)-1;
 
-  CommSize = sizeof(EFI_GUID) + sizeof(UINTN) + CommHeader->MessageLength;
+  //
+  // The CommHeader->MessageLength contains a definitive value, thus UINTN cast is safe here.
+  //
+  CommSize = OFFSET_OF(EFI_SMM_COMMUNICATE_HEADER, Data) + (UINTN)CommHeader->MessageLength;
   Buffer = (UINT8 *)CommHeader + CommSize;
   Size -= CommSize;
 
-- 
2.31.1.windows.1