Re: [PATCH] Shellpkg/editor: Fix a bug that may modifies Line[-1]

["Carsey, Jaben" <jaben.carsey@intel.com>]

Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>

> -----Original Message-----
> From: Ni, Ruiyu
> Sent: Tuesday, October 24, 2017 6:03 PM
> To: edk2-devel@lists.01.org
> Cc: Carsey, Jaben <jaben.carsey@intel.com>; Wu, Hao A
> <hao.a.wu@intel.com>
> Subject: [PATCH] Shellpkg/editor: Fix a bug that may modifies Line[-1]
> Importance: High
> 
> The original code as below intend to set the character
> before last column to CHAR_NULL.
>   Line[(LastCol % (ARRAY_SIZE (Line) - 1)) - 1] = CHAR_NULL;
> 
> But when LastCol % (ARRAY_SIZE (Line) - 1)) equals to 0,
> Line[-1] is modified.
> 
> We should change to code as below:
>   Line[(LastCol - 1) % (ARRAY_SIZE (Line) - 1)] = CHAR_NULL;
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Jaben Carsey <jaben.carsey@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> ---
>  .../Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
> | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git
> a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> dsLib.c
> b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> dsLib.c
> index d26d08f95c..b45e9a33f3 100644
> ---
> a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> dsLib.c
> +++
> b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1Comman
> dsLib.c
> @@ -205,7 +205,7 @@ EditorClearLine (
>          //
>          // if CHAR_NULL is still at position LastCol, it will cause first line error
>          //
> -        Line[(LastCol % (ARRAY_SIZE (Line) - 1)) - 1] = CHAR_NULL;
> +        Line[(LastCol - 1) % (ARRAY_SIZE (Line) - 1)] = CHAR_NULL;
>        } else {
>          Line[LastCol % (ARRAY_SIZE (Line) - 1)] = CHAR_NULL;
>        }
> --
> 2.12.2.windows.2