Re: [edk2-devel] [PATCH v3 4/4] StandaloneMmPkg/Core: Fix the failure to find uncompressed inner FV

["Laszlo Ersek" <lersek@redhat.com>]

On 10/30/23 08:49, Wei6 Xu wrote:
> The MmCoreFfsFindMmDriver only checks for encapsulated compressed FVs.
> When an inner FV is uncompressed, StandaloneMmCore will miss the FV and
> all the MM drivers in the FV will not be dispatched.
> Add checks for uncompressed inner FV to fix this issue.
> 
> 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>
> ---
>  StandaloneMmPkg/Core/FwVol.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/StandaloneMmPkg/Core/FwVol.c b/StandaloneMmPkg/Core/FwVol.c
> index fa335d62c252..783dbaf9b048 100644
> --- a/StandaloneMmPkg/Core/FwVol.c
> +++ b/StandaloneMmPkg/Core/FwVol.c
> @@ -116,6 +116,25 @@ MmCoreFfsFindMmDriver (
>        break;
>      }
>  
> +    //
> +    // Check uncompressed firmware volumes
> +    //
> +    Status = FfsFindSectionData (
> +               EFI_SECTION_FIRMWARE_VOLUME_IMAGE,
> +               FileHeader,
> +               &SectionData,
> +               &SectionDataSize
> +               );
> +    if (!EFI_ERROR (Status)) {
> +      if (SectionDataSize > sizeof (EFI_FIRMWARE_VOLUME_HEADER)) {
> +        InnerFvHeader = (EFI_FIRMWARE_VOLUME_HEADER *)SectionData;
> +        MmCoreFfsFindMmDriver (InnerFvHeader, Depth + 1);
> +      }
> +    }
> +
> +    //
> +    // Check compressed firmware volumes
> +    //
>      Status = FfsFindSection (
>                 EFI_SECTION_GUID_DEFINED,
>                 FileHeader,

(1) In case we find an EFI_SECTION_FIRMWARE_VOLUME_IMAGE, do we still want to look for an EFI_SECTION_GUID_DEFINED?

I think that's quite unlikely. If you agree, can you add a "continue" right after the new MmCoreFfsFindMmDriver() call?

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

(2) We have a separate "InnerFvHeader" assignment, near the bottom of this (first) loop in the function:

     Status = FindFfsSectionInSections (
                DstBuffer,
                DstBufferSize,
                EFI_SECTION_FIRMWARE_VOLUME_IMAGE,
                &Section
                );
     if (EFI_ERROR (Status)) {
       goto FreeDstBuffer;
     }
 
     InnerFvHeader = (VOID *)(Section + 1);
     Status        = MmCoreFfsFindMmDriver (InnerFvHeader, Depth + 1);

That doesn't look right to me; what if Section in fact points to an EFI_COMMON_SECTION_HEADER2?

FfsFindSectionData() handles this internally; it checks IS_SECTION2(), and then adjusts SectionData accordingly:

      if (IS_SECTION2 (Section)) {
        *SectionData     = (VOID *)((EFI_COMMON_SECTION_HEADER2 *)Section + 1);
        ...
      } else {
        *SectionData     = (VOID *)(Section + 1);
        ...
      }

I think we need to set InnerFvHeader similarly, here. Can you please append a separate patch for fixing that?

Thanks!
Laszlo



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