Re: [edk2-devel] [PATCH] MdeModulePkg/HiiDatabaseDxe: Add check for 'Private->Attribute >> 4'

["Dandan Bi" <dandan.bi@intel.com>]

> -----Original Message-----
> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> Zhang, Shenglei
> Sent: Thursday, October 17, 2019 2:21 PM
> To: devel@edk2.groups.io
> Cc: Bi, Dandan <dandan.bi@intel.com>; Dong, Eric <eric.dong@intel.com>
> Subject: [edk2-devel] [PATCH] MdeModulePkg/HiiDatabaseDxe: Add check
> for 'Private->Attribute >> 4'
> 
> The size of mHiiEfiColors is 16.
> mHiiEfiColors[Private->Attribute >> 4] may be out of boundary.
> So add a check for that.
> 
> Cc: Dandan Bi <dandan.bi@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
> ---
>  MdeModulePkg/Universal/HiiDatabaseDxe/Font.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
> b/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
> index ca63df168c94..282a7a114d17 100644
> --- a/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
> +++ b/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
> @@ -999,7 +999,12 @@ GetSystemFont (
>    }
> 
>    Info->ForegroundColor    = mHiiEfiColors[Private->Attribute & 0x0f];
> -  Info->BackgroundColor    = mHiiEfiColors[Private->Attribute >> 4];
> +  if ((Private->Attribute >> 4) < 16){
> +    Info->BackgroundColor    = mHiiEfiColors[Private->Attribute >> 4];
> +  } else {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
Hi Shenglei,

Foreground and background color are saved in a single byte. Bits 0..3 are the foreground color and bits 4..6 are the background color.
If the Private->Attribute defined correctly, then (Private->Attribute >> 4) must less than 8. And in current code Private->Attribute is defined as EFI_TEXT_ATTR (EFI_LIGHTGRAY, EFI_BLACK) in HiiDatabaseEntry.c, so the (Private->Attribute >> 4) will not overflow. I think we can add ASSERT code instead.


Thanks,
Dandan
>    Info->FontInfoMask       = EFI_FONT_INFO_SYS_FONT |
> EFI_FONT_INFO_SYS_SIZE | EFI_FONT_INFO_SYS_STYLE;
>    Info->FontInfo.FontStyle = 0;
>    Info->FontInfo.FontSize  = EFI_GLYPH_HEIGHT;
> --
> 2.18.0.windows.1
> 
> 
>