From c83ffd267680806483eb22c1cd9c9af83b8aa708 Mon Sep 17 00:00:00 2001
From: Zhiguang Liu <zhiguang.liu@intel.com>
Date: Mon, 27 Nov 2023 14:41:52 +0800
Subject: [PATCH] UefiCpuPkg/CpuPageTableLib: Init local variable before using
 it.

The local variable OneOfPagingEntry is used before initialized, this
may cause reserved bit in page table entry is set especially in PAE
paging mode. The bug is random because it depends on the value in
stack.

Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
---
 UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
index eff02619fa..36b2c4e6a3 100644
--- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
+++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
@@ -338,7 +338,7 @@ PageTableLibMapInLevel (
   ParentAttribute             = &LocalParentAttribute;
 
   OriginalParentPagingEntry.Uint64 = ParentPagingEntry->Uint64;
-
+  OneOfPagingEntry.Uint64          = 0;
   //
   // RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21) or 4K (1 << 12).
   //
@@ -367,8 +367,6 @@ PageTableLibMapInLevel (
       if (RETURN_ERROR (Status)) {
         return Status;
       }
-
-      OneOfPagingEntry.Pnle.Uint64 = 0;
     } else {
       PageTableLibSetPle (Level, &OneOfPagingEntry, 0, &PleBAttribute, &AllOneMask);
     }