Reviewed-by: Andrew Fish <afish@apple.com>

Thanks,

Andrew Fish

> On Jul 16, 2019, at 9:58 AM, Carsey, Jaben <jaben.carsey@intel.com> wrote:
> 
> Reviewed-by: Jaben Carsey <jaben.carsey@intel.com <mailto:jaben.carsey@intel.com>>
> 
> Thanks
> -Jaben
> 
>> -----Original Message-----
>> From: Gao, Zhichao
>> Sent: Tuesday, July 16, 2019 2:12 AM
>> To: devel@edk2.groups.io <mailto:devel@edk2.groups.io>
>> Cc: Carsey, Jaben <jaben.carsey@intel.com <mailto:jaben.carsey@intel.com>>; Ni, Ray <ray.ni@intel.com <mailto:ray.ni@intel.com>>;
>> Andrew Fish <afish@apple.com <mailto:afish@apple.com>>
>> Subject: [PATCH V2] ShellPkg/Type.c: Add value check before (LoopVar - 1)
>> 
>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1964
>> 
>> If the file begin with single line Feed ('\n'), then
>> "AsciiChar == '\n' && ((CHAR8*)Buffer)[LoopVar-1] != '\r'"
>> would cause a underflow. Add this condition
>> "(AsciiChar == '\n' && LoopVar == 0)" before it to make sure
>> (LoopVar - 1) would never encounter a underflow.
>> 
>> Same change in Unicode section.
>> 
>> Cc: Jaben Carsey <jaben.carsey@intel.com>
>> Cc: Ray Ni <ray.ni@intel.com>
>> Cc: Andrew Fish <afish@apple.com>
>> Signed-off-by: Zhichao Gao <zhichao.gao@intel.com>
>> ---
>> V2:
>> 1. Update the copyright
>> 2. Fix the same issue in unicode section
>> 3. Fix typo
>> 
>> .../Library/UefiShellLevel3CommandsLib/Type.c | 24 ++++++++++---------
>> 1 file changed, 13 insertions(+), 11 deletions(-)
>> 
>> diff --git a/ShellPkg/Library/UefiShellLevel3CommandsLib/Type.c
>> b/ShellPkg/Library/UefiShellLevel3CommandsLib/Type.c
>> index 4efc0a8e24..f0aa57af3d 100644
>> --- a/ShellPkg/Library/UefiShellLevel3CommandsLib/Type.c
>> +++ b/ShellPkg/Library/UefiShellLevel3CommandsLib/Type.c
>> @@ -2,7 +2,7 @@
>>   Main file for Type shell level 3 function.
>> 
>>   (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.<BR>
>> -  Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved. <BR>
>> +  Copyright (c) 2009 - 2019, Intel Corporation. All rights reserved. <BR>
>>   SPDX-License-Identifier: BSD-2-Clause-Patent
>> 
>> **/
>> @@ -78,12 +78,13 @@ TypeFileByHandle (
>>           // Allow Line Feed (LF) (0xA) & Carriage Return (CR) (0xD)
>>           // characters to be displayed as is.
>>           //
>> -          if (AsciiChar == '\n' && ((CHAR8*)Buffer)[LoopVar-1] != '\r') {
>> +          if ((AsciiChar == '\n' && LoopVar == 0) ||
>> +              (AsciiChar == '\n' && ((CHAR8*)Buffer)[LoopVar-1] != '\r')) {
>>             //
>> -            // In case Line Feed (0xA) is encountered & Carriage Return (0xD)
>> -            // was not the previous character, print CR and LF. This is because
>> -            // Shell 2.0 requires carriage return with line feed for displaying
>> -            // each new line from left.
>> +            // In case file begin with single line Feed or Line Feed (0xA) is
>> +            // encountered & Carriage Return (0xD) was not previous character,
>> +            // print CR and LF. This is because Shell 2.0 requires carriage
>> +            // return with line feed for displaying each new line from left.
>>             //
>>             ShellPrintEx (-1, -1, L"\r\n");
>>             continue;
>> @@ -121,12 +122,13 @@ TypeFileByHandle (
>>           // Allow Line Feed (LF) (0xA) & Carriage Return (CR) (0xD)
>>           // characters to be displayed as is.
>>           //
>> -          if (Ucs2Char == '\n' && ((CHAR16*)Buffer)[LoopVar-1] != '\r') {
>> +          if ((Ucs2Char == '\n' && LoopVar == 0) ||
>> +              (Ucs2Char == '\n' && ((CHAR16*)Buffer)[LoopVar-1] != '\r')) {
>>             //
>> -            // In case Line Feed (0xA) is encountered & Carriage Return (0xD)
>> -            // was not the previous character, print CR and LF. This is because
>> -            // Shell 2.0 requires carriage return with line feed for displaying
>> -            // each new line from left.
>> +            // In case file begin with single line Feed or Line Feed (0xA) is
>> +            // encountered & Carriage Return (0xD) was not previous character,
>> +            // print CR and LF. This is because Shell 2.0 requires carriage
>> +            // return with line feed for displaying each new line from left.
>>             //
>>             ShellPrintEx (-1, -1, L"\r\n");
>>             continue;
>> --
>> 2.21.0.windows.1
> 
> 
>