Re: [PATCH 4/6] MdeModulePkg/DxeNetLib: Rewrite NetblockChecksum function logic

["Wu, Jiaxin" <jiaxin.wu@intel.com>]

Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>


> -----Original Message-----
> From: Wu, Hao A
> Sent: Wednesday, December 14, 2016 7:27 PM
> To: edk2-devel@lists.01.org
> Cc: Wu, Hao A <hao.a.wu@intel.com>; Fu, Siyuan <siyuan.fu@intel.com>; Ye,
> Ting <ting.ye@intel.com>; Wu, Jiaxin <jiaxin.wu@intel.com>
> Subject: [PATCH 4/6] MdeModulePkg/DxeNetLib: Rewrite
> NetblockChecksum function logic
> 
> This commit rewrites the logic for NetblockChecksum. It processes the
> checksum of the left-over byte first to prevent possible mis-reports by static
> code checkers.
> 
> Cc: Fu Siyuan <siyuan.fu@intel.com>
> Cc: Ye Ting <ting.ye@intel.com>
> Cc: Wu Jiaxin <jiaxin.wu@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Hao Wu <hao.a.wu@intel.com>
> ---
>  MdeModulePkg/Library/DxeNetLib/NetBuffer.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/MdeModulePkg/Library/DxeNetLib/NetBuffer.c
> b/MdeModulePkg/Library/DxeNetLib/NetBuffer.c
> index bbbdbc0..95cb717 100644
> --- a/MdeModulePkg/Library/DxeNetLib/NetBuffer.c
> +++ b/MdeModulePkg/Library/DxeNetLib/NetBuffer.c
> @@ -1,7 +1,7 @@
>  /** @file
>    Network library functions providing net buffer operation support.
> 
> -Copyright (c) 2005 - 2010, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2005 - 2016, Intel Corporation. All rights reserved.<BR>
>  This program and the accompanying materials  are licensed and made
> available under the terms and conditions of the BSD License  which
> accompanies this distribution.  The full text of the license may be found at
> @@ -1661,6 +1661,13 @@ NetblockChecksum (
> 
>    Sum = 0;
> 
> +  //
> +  // Add left-over byte, if any
> +  //
> +  if (Len % 2 != 0) {
> +    Sum += *(Bulk + Len - 1);
> +  }
> +
>    while (Len > 1) {
>      Sum += *(UINT16 *) Bulk;
>      Bulk += 2;
> @@ -1668,13 +1675,6 @@ NetblockChecksum (
>    }
> 
>    //
> -  // Add left-over byte, if any
> -  //
> -  if (Len > 0) {
> -    Sum += *(UINT8 *) Bulk;
> -  }
> -
> -  //
>    // Fold 32-bit sum to 16 bits
>    //
>    while ((Sum >> 16) != 0) {
> --
> 1.9.5.msysgit.0