MdeModulePkg/Core: fix guard page missing issue

This issue is a regression one caused by a patch at

    425d25699be83c35e12df8470b827d7fbcef3bce

That fix didn't take the 0 page to free into account, which still
needs to call UnsetGuardPage() even no memory needs to free.

The fix is just moving the calling of UnsetGuardPage() to the place
right after calling AdjustMemoryF().

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

2 files changed, 11 insertions, 12 deletions

diff --git a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
index 92753c7..392aeb8 100644
--- a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
+++ b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
@@ -1135,10 +1135,6 @@ CoreConvertPagesWithGuard (
     OldPages = NumberOfPages;

 

     AdjustMemoryF (&Start, &NumberOfPages);

-    if (NumberOfPages == 0) {

-      return EFI_SUCCESS;

-    }

-

     //

     // It's safe to unset Guard page inside memory lock because there should

     // be no memory allocation occurred in updating memory page attribute at

@@ -1147,6 +1143,9 @@ CoreConvertPagesWithGuard (
     // marking it usable (from non-present to present).

     //

     UnsetGuardForMemory (OldStart, OldPages);

+    if (NumberOfPages == 0) {

+      return EFI_SUCCESS;

+    }

   } else {

     AdjustMemoryA (&Start, &NumberOfPages);

   }

diff --git a/MdeModulePkg/Core/Dxe/Mem/Pool.c b/MdeModulePkg/Core/Dxe/Mem/Pool.c
index df9a1d2..1ff2061 100644
--- a/MdeModulePkg/Core/Dxe/Mem/Pool.c
+++ b/MdeModulePkg/Core/Dxe/Mem/Pool.c
@@ -642,15 +642,15 @@ CoreFreePoolPagesWithGuard (
   NoPagesGuarded = NoPages;

 

   AdjustMemoryF (&Memory, &NoPages);

+  //

+  // It's safe to unset Guard page inside memory lock because there should

+  // be no memory allocation occurred in updating memory page attribute at

+  // this point. And unsetting Guard page before free will prevent Guard

+  // page just freed back to pool from being allocated right away before

+  // marking it usable (from non-present to present).

+  //

+  UnsetGuardForMemory (MemoryGuarded, NoPagesGuarded);

   if (NoPages > 0) {

-    //

-    // It's safe to unset Guard page inside memory lock because there should

-    // be no memory allocation occurred in updating memory page attribute at

-    // this point. And unsetting Guard page before free will prevent Guard

-    // page just freed back to pool from being allocated right away before

-    // marking it usable (from non-present to present).

-    //

-    UnsetGuardForMemory (MemoryGuarded, NoPagesGuarded);

     CoreFreePoolPagesI (PoolType, Memory, NoPages);

   }

 }