StandaloneMmPkg: Fix section data length returned larger than actual data

This change fixes an issue where the returned section data length
is always 4 bytes larger than the actual section length. This could
cause an issue where the caller accesses the final 4 bytes which
would be invalid.

Co-authored-by: Kun Qin <kuqin@microsoft.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>

2 files changed, 8 insertions, 8 deletions

diff --git a/StandaloneMmPkg/Include/Library/FvLib.h b/StandaloneMmPkg/Include/Library/FvLib.h
index 1eb9ea7e04..3b603e473d 100644
--- a/StandaloneMmPkg/Include/Library/FvLib.h
+++ b/StandaloneMmPkg/Include/Library/FvLib.h
@@ -87,7 +87,7 @@ FindFfsSectionInSections (
   @param  FfsFileHeader   Pointer to the current file to search.

   @param  SectionData     Pointer to the Section matching SectionType in FfsFileHeader.

                           NULL if section not found

-  @param  SectionDataSize The size of SectionData

+  @param  SectionDataSize The size of SectionData, excluding the section header.

 

   @retval  EFI_NOT_FOUND  No files matching the search criteria were found

   @retval  EFI_SUCCESS

diff --git a/StandaloneMmPkg/Library/FvLib/FvLib.c b/StandaloneMmPkg/Library/FvLib/FvLib.c
index 89504b9ee9..e0f344af38 100644
--- a/StandaloneMmPkg/Library/FvLib/FvLib.c
+++ b/StandaloneMmPkg/Library/FvLib/FvLib.c
@@ -338,11 +338,11 @@ FfsFindSection (
   Given the input file pointer, search for the next matching section in the

   FFS volume.

 

-  @param  SearchType      Filter to find only sections of this type.

-  @param  FfsFileHeader   Pointer to the current file to search.

-  @param  SectionData     Pointer to the Section matching SectionType in FfsFileHeader.

-                          NULL if section not found

-  @param  SectionDataSize The size of SectionData

+  @param[in]      SectionType     Filter to find only sections of this type.

+  @param[in]      FfsFileHeader   Pointer to the current file to search.

+  @param[in,out]  SectionData     Pointer to the Section matching SectionType in FfsFileHeader.

+                                  NULL if section not found

+  @param[in,out]  SectionDataSize The size of SectionData, excluding the section header.

 

   @retval  EFI_NOT_FOUND  No files matching the search criteria were found

   @retval  EFI_SUCCESS

@@ -380,10 +380,10 @@ FfsFindSectionData (
     if (Section->Type == SectionType) {

       if (IS_SECTION2 (Section)) {

         *SectionData     = (VOID *)((EFI_COMMON_SECTION_HEADER2 *)Section + 1);

-        *SectionDataSize = SECTION2_SIZE (Section);

+        *SectionDataSize = SECTION2_SIZE (Section) - sizeof (EFI_COMMON_SECTION_HEADER2);

       } else {

         *SectionData     = (VOID *)(Section + 1);

-        *SectionDataSize = SECTION_SIZE (Section);

+        *SectionDataSize = SECTION_SIZE (Section) - sizeof (EFI_COMMON_SECTION_HEADER);

       }

 

       return EFI_SUCCESS;