Re: [PATCH] UefiCpuPkg/Microcode.c: Add verification before calculate CheckSum32

["Ni, Ray" <ray.ni@intel.com>]

Reviewed-by: Ray Ni <ray.ni@intel.com>

> -----Original Message-----
> From: edk2-devel <edk2-devel-bounces@lists.01.org> On Behalf Of Chen A
> Chen
> Sent: Tuesday, March 5, 2019 8:21 AM
> To: edk2-devel@lists.01.org
> Cc: Dong, Eric <eric.dong@intel.com>
> Subject: [edk2] [PATCH] UefiCpuPkg/Microcode.c: Add verification before
> calculate CheckSum32
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1020
> 
> Should make sure the TotalSize of Microcode is aligned with 4 bytes
> before calling CalculateSum32 function.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Chen A Chen <chen.a.chen@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/Microcode.c | 31 ++++++++++++++++++++--
> ---------
>  1 file changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c
> b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> index 5f9ae22794..643a6f94f4 100644
> --- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
> +++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> @@ -166,20 +166,29 @@ MicrocodeDetect (
>      //
>      CorrectMicrocode = FALSE;
> 
> -    //
> -    // Save an in-complete CheckSum32 from CheckSum Part1 for common
> parts.
> -    //
>      if (MicrocodeEntryPoint->DataSize == 0) {
> -      InCompleteCheckSum32 = CalculateSum32 (
> -                               (UINT32 *) MicrocodeEntryPoint,
> -                               sizeof (CPU_MICROCODE_HEADER) + 2000
> -                               );
> +      TotalSize = sizeof (CPU_MICROCODE_HEADER) + 2000;
>      } else {
> -      InCompleteCheckSum32 = CalculateSum32 (
> -                               (UINT32 *) MicrocodeEntryPoint,
> -                               sizeof (CPU_MICROCODE_HEADER) + MicrocodeEntryPoint-
> >DataSize
> -                               );
> +      TotalSize = sizeof (CPU_MICROCODE_HEADER) + MicrocodeEntryPoint-
> >DataSize;
>      }
> +
> +    ///
> +    /// Check overflow and whether TotalSize is aligned with 4 bytes.
> +    ///
> +    if ( ((UINTN)MicrocodeEntryPoint + TotalSize) > MicrocodeEnd ||
> +         (TotalSize & 0x3) != 0
> +       ) {
> +      MicrocodeEntryPoint = (CPU_MICROCODE_HEADER *) (((UINTN)
> MicrocodeEntryPoint) + SIZE_1KB);
> +      continue;
> +    }
> +
> +    //
> +    // Save an in-complete CheckSum32 from CheckSum Part1 for common
> parts.
> +    //
> +    InCompleteCheckSum32 = CalculateSum32 (
> +                             (UINT32 *) MicrocodeEntryPoint,
> +                             TotalSize
> +                             );
>      InCompleteCheckSum32 -= MicrocodeEntryPoint-
> >ProcessorSignature.Uint32;
>      InCompleteCheckSum32 -= MicrocodeEntryPoint->ProcessorFlags;
>      InCompleteCheckSum32 -= MicrocodeEntryPoint->Checksum;
> --
> 2.16.2.windows.1
> 
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