Re: [PATCH 1/2] MdeModulePkg/UdfDxe: reject reserved values in ICB.Flags[2:0]

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

Thanks/Ray

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Wednesday, September 13, 2017 6:26 AM
> To: edk2-devel-01 <edk2-devel@lists.01.org>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Dong, Eric
> <eric.dong@intel.com>; Paulo Alcantara <pcacjr@zytor.com>; Ni, Ruiyu
> <ruiyu.ni@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: [PATCH 1/2] MdeModulePkg/UdfDxe: reject reserved values in
> ICB.Flags[2:0]
> 
> The ECMA-167 standard (3rd Edition, June 1997) reserves values 4 through 7
> in the ICB.Flags[2:0] bit-field for future standardization; see "14.6 ICB Tag" /
> "14.6.8 Flags (RBP 18)".
> 
> https://www.ecma-international.org/publications/standards/Ecma-167.htm
> 
> The
> 
>   switch (RecordingFlags)
> 
> statement in the ReadFile() function handles all the standard values, using
> the constants of the UDF_FE_RECORDING_FLAGS enum type. However, the
> reserved values are not caught with a "default" case label, which both breaks
> the edk2 Coding Style Spec, and leaves the Status variable un-initialized,
> before we return Status under the Done label.
> 
> Set Status to EFI_UNSUPPORTED if we encounter a reserved value.
> 
> This issue was reported by Ard's and Gerd's CI systems independently
> (through build failures with GCC48/GCC49, DEBUG/RELEASE targets).
> 
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Paulo Alcantara <pcacjr@zytor.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Star Zeng <star.zeng@intel.com>
> Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Reported-by: Gerd Hoffmann <kraxel@redhat.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
>  MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c | 8
> ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
> b/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
> index 72862653738e..096fbb4452cb 100644
> --- a/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
> +++ b/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
> @@ -1150,6 +1150,14 @@ ReadFile (
>      ASSERT (FALSE);
>      Status = EFI_UNSUPPORTED;
>      break;
> +
> +  default:
> +    //
> +    // A flag value reserved by the ECMA-167 standard (3rd Edition - June
> +    // 1997); 14.6 ICB Tag; 14.6.8 Flags (RBP 18); was found.
> +    //
> +    Status = EFI_UNSUPPORTED;
> +    break;
>    }
> 
>  Done:
> --
> 2.14.1.3.gb7cf6e02401b
>