Re: [Patch] UefiCpuPkg/PiSmmCpuDxeSmm: Add check to void use null pointer.

["Wu, Hao A" <hao.a.wu@intel.com>]

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Eric
> Dong
> Sent: Monday, October 09, 2017 11:18 AM
> To: edk2-devel@lists.01.org
> Cc: Ni, Ruiyu
> Subject: [edk2] [Patch] UefiCpuPkg/PiSmmCpuDxeSmm: Add check to void use
> null pointer.
> 
> Current code logic not check the pointer before use it. This may
> has potential issue, this patch add code to check it.
> 
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Eric Dong <eric.dong@intel.com>
> ---
>  UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
> index ef72b9b..2c1dc82 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
> @@ -226,12 +226,17 @@ SetProcessorRegister (
>    CPU_REGISTER_TABLE        *RegisterTable;
> 
>    InitApicId = GetInitialApicId ();
> +  RegisterTable = NULL;
>    for (Index = 0; Index < RegisterTableCount; Index++) {
>      if (RegisterTables[Index].InitialApicId == InitApicId) {
>        RegisterTable =  &RegisterTables[Index];
>        break;
>      }
>    }
> +  ASSERT (RegisterTable != NULL);
> +  if (RegisterTable == NULL) {
> +    return;
> +  }

Hi Eric,

If "RegisterTable == NULL" is a case that should never occur, my thought
is that using "ASSERT" merely is enough. The 'if' statement above seems
can be removed for me.


Best Regards,
Hao Wu

> 
>    //
>    // Traverse Register Table of this logical processor
> --
> 2.7.0.windows.1
> 
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