Re: [PATCH v1 03/11] ShellPkg: acpiview: FADT: Validate global pointer before use

["Krzysztof Koch" <krzysztof.koch@arm.com>]

Hi Zhichao,

I think you're right. I will submit a v2 patch that minimizes the amount of pointer validation required for parsing the remaining tables.

Kind regards,

Krzysztof

-----Original Message-----
From: Gao, Zhichao <zhichao.gao@intel.com> 
Sent: Friday, August 16, 2019 8:35
To: Krzysztof Koch <Krzysztof.Koch@arm.com>; devel@edk2.groups.io
Cc: Carsey, Jaben <jaben.carsey@intel.com>; Ni, Ray <ray.ni@intel.com>; Sami Mujawar <Sami.Mujawar@arm.com>; Matteo Carlini <Matteo.Carlini@arm.com>; nd <nd@arm.com>
Subject: RE: [PATCH v1 03/11] ShellPkg: acpiview: FADT: Validate global pointer before use

For FadtMinorRevision and X_DsdtAddress, I don't think they are required section. Maybe we should consider check the length before check them. As I know, the OVMF's FACP table doesn't have the section after flag.

Thanks,
Zhichao

> -----Original Message-----
> From: Krzysztof Koch [mailto:krzysztof.koch@arm.com]
> Sent: Thursday, August 15, 2019 9:11 PM
> To: devel@edk2.groups.io
> Cc: Carsey, Jaben <jaben.carsey@intel.com>; Ni, Ray 
> <ray.ni@intel.com>; Gao, Zhichao <zhichao.gao@intel.com>; 
> Sami.Mujawar@arm.com; Matteo.Carlini@arm.com; nd@arm.com
> Subject: [PATCH v1 03/11] ShellPkg: acpiview: FADT: Validate global 
> pointer before use
> 
> Check if global pointers have been successfully updated before they 
> are used for further table parsing.
> 
> Signed-off-by: Krzysztof Koch <krzysztof.koch@arm.com>
> ---
> 
> Notes:
>     v1:
>     - Test against NULL pointers [Krzysztof]
> 
>  
> ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.c
> | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git
> a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.
> c
> b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.
> c
> index
> e40c9ef8ee4b3285faf8c6edf3cb6236ee367397..e218e45926abced1096e75441
> e22108db7a3a811 100644
> ---
> a/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtParser.
> c
> +++
> b/ShellPkg/Library/UefiShellAcpiViewCommandLib/Parsers/Fadt/FadtPars
> +++ er.c
> @@ -203,6 +203,20 @@ ParseAcpiFadt (
>      PARSER_PARAMS (FadtParser)
>      );
> 
> +  // Check if the values used to control the parsing logic have been 
> + // successfully read.
> +  if ((DsdtAddress == NULL)       ||
> +      (FadtMinorRevision == NULL) ||
> +      (X_DsdtAddress == NULL)) {
> +    IncrementErrorCount ();
> +    Print (
> +      L"ERROR: Insufficient table length. AcpiTableLength = %d. " \
> +        L"FADT parsing aborted.\n",
> +      AcpiTableLength
> +      );
> +    return;
> +  }
> +
>    if (Trace) {
>      Print (L"\nSummary:\n");
>      PrintFieldName (2, L"FADT Version");
> --
> 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
>