Re: [PATCH] UefiCpuPkg RegisterCpuFeaturesLib: NumberOfCpus may be uninitialized

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

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

> -----Original Message-----
> From: Zeng, Star <star.zeng@intel.com>
> Sent: Thursday, January 21, 2021 5:38 PM
> Cc: Zeng, Star <star.zeng@intel.com>; Dong, Eric <eric.dong@intel.com>; Ni,
> Ray <ray.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>
> Subject: [PATCH] UefiCpuPkg RegisterCpuFeaturesLib: NumberOfCpus may be
> uninitialized
> 
> NumberOfCpus local variable in GetAcpiCpuData will be uninitialized
> when CpuS3DataDxe runs before DxeRegisterCpuFeaturesLib (linked by
> CpuFeaturesDxe) because there is no code to initialize it at
> (AcpiCpuData != NULL) execution path.
> 
> The issue is exposed after cefad282fb31aff3e1a6dcbd368cbbffc3fce900
> and 38ee7bafa72f58982f99ac6f61eef160f80bad69.
> There was negligence in that code review.
> One further topic may be "Could EDK2 CI be enhanced to catch this kind
> of uninitialized local variable case?". :)
> 
> This patch fixes this regression issue.
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Signed-off-by: Star Zeng <star.zeng@intel.com>
> ---
>  .../Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c      | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git
> a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> index 7bb92404027f..60daa5cc87f0 100644
> --- a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> +++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> @@ -957,6 +957,7 @@ GetAcpiCpuData (
>      //
>      // Allocate buffer for empty RegisterTable and PreSmmInitRegisterTable for
> all CPUs
>      //
> +    NumberOfCpus = AcpiCpuData->NumberOfCpus;
>      TableSize = 2 * NumberOfCpus * sizeof (CPU_REGISTER_TABLE);
>      RegisterTable  = AllocatePages (EFI_SIZE_TO_PAGES (TableSize));
>      ASSERT (RegisterTable != NULL);
> --
> 2.27.0.windows.1