From: Ruiyu Ni <ruiyu.ni@intel.com>
Date: Wed, 25 Oct 2017 01:01:27 +0000 (+0800)
Subject: Shellpkg/editor: Fix a bug that may modifies Line[-1]
X-Git-Tag: edk2-stable201903~3181
X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=commitdiff_plain;h=452676ffd895651683dcf19535e65294ff1d00d0

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

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>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
---

diff --git a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
index d26d08f95c..b45e9a33f3 100644
--- a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c
+++ b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.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;
       }