From: Shenglei Zhang <shenglei.zhang@intel.com>
Date: Mon, 25 Feb 2019 05:55:54 +0000 (+0800)
Subject: MdePkg/BaseUefiDecompressLib: Improve performance of boundary validation
X-Git-Tag: edk2-stable201905~417
X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=commitdiff_plain;h=8028f03032182f2c72e7699e1d14322bb5586581

MdePkg/BaseUefiDecompressLib: Improve performance of boundary validation

The boundary validation checking in MakeTable() performs on
every loop iteration. This could be improved by checking
just once before the loop.
https://bugzilla.tianocore.org/show_bug.cgi?id=1329

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
---

diff --git a/MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.c b/MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.c
index c1e8c5581a..3d5b7a737a 100644
--- a/MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.c
+++ b/MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.c
@@ -222,10 +222,11 @@ MakeTable (
 
     if (Len <= TableBits) {
 
+      if (Start[Len] >= NextCode || NextCode > MaxTableLength){
+        return (UINT16) BAD_TABLE;
+      }
+
       for (Index = Start[Len]; Index < NextCode; Index++) {
-        if (Index >= MaxTableLength) {
-          return (UINT16) BAD_TABLE;
-        }
         Table[Index] = Char;
       }