From a5ea259b2864b25b62bf1bb4045c6961877a342a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Gardou?= <jerome.gardou@reactos.org>
Date: Tue, 1 Jun 2021 10:32:12 +0200
Subject: [PATCH] [NTOS:MM] Fix remnants of CORE-17587

---
 ntoskrnl/mm/i386/page.c | 26 +++++++++++++++++---------
 ntoskrnl/mm/section.c   |  2 +-
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/ntoskrnl/mm/i386/page.c b/ntoskrnl/mm/i386/page.c
index 3e5f5797218..d15a9f74964 100644
--- a/ntoskrnl/mm/i386/page.c
+++ b/ntoskrnl/mm/i386/page.c
@@ -540,6 +540,10 @@ MmCreateVirtualMappingUnsafe(PEPROCESS Process,
     /* Make sure our PDE is valid, and that everything is going fine */
     if (Process == NULL)
     {
+        /* We don't support this in legacy Mm for kernel mappings */
+        ASSERT(ProtectionMask != MM_WRITECOPY);
+        ASSERT(ProtectionMask != MM_EXECUTE_WRITECOPY);
+
         if (Address < MmSystemRangeStart)
         {
             DPRINT1("NULL process given for user-mode mapping at %p\n", Address);
@@ -567,14 +571,7 @@ MmCreateVirtualMappingUnsafe(PEPROCESS Process,
 
     PointerPte = MiAddressToPte(Address);
 
-    if (Address >= MmSystemRangeStart)
-    {
-        MI_MAKE_HARDWARE_PTE_KERNEL(&TempPte, PointerPte, ProtectionMask, Page);
-    }
-    else
-    {
-        MI_MAKE_HARDWARE_PTE_USER(&TempPte, PointerPte, ProtectionMask, Page);
-    }
+    MI_MAKE_HARDWARE_PTE(&TempPte, PointerPte, ProtectionMask, Page);
 
     Pte = InterlockedExchangePte(PointerPte, TempPte.u.Long);
     /* There should not have been anything valid here */
@@ -710,7 +707,18 @@ MmSetPageProtect(PEPROCESS Process, PVOID Address, ULONG flProtect)
 
     PointerPte = MiAddressToPte(Address);
 
-    MI_MAKE_HARDWARE_PTE_USER(&TempPte, PointerPte, ProtectionMask, PFN_FROM_PTE(PointerPte));
+    /* Sanity check */
+    ASSERT(PointerPte->u.Hard.Owner == 1);
+
+    TempPte.u.Long = 0;
+    TempPte.u.Hard.PageFrameNumber = PointerPte->u.Hard.PageFrameNumber;
+    TempPte.u.Long |= MmProtectToPteMask[ProtectionMask];
+    TempPte.u.Hard.Owner = 1;
+
+    /* Only set valid bit if we have to */
+    if ((ProtectionMask != MM_NOACCESS) && !FlagOn(ProtectionMask, MM_GUARDPAGE))
+        TempPte.u.Hard.Valid = 1;
+
     /* Keep dirty & accessed bits */
     TempPte.u.Hard.Accessed = PointerPte->u.Hard.Accessed;
     TempPte.u.Hard.Dirty = PointerPte->u.Hard.Dirty;
diff --git a/ntoskrnl/mm/section.c b/ntoskrnl/mm/section.c
index 005e686e771..c6b618cdbf8 100644
--- a/ntoskrnl/mm/section.c
+++ b/ntoskrnl/mm/section.c
@@ -1474,7 +1474,7 @@ MmAlterViewAttributes(PMMSUPPORT AddressSpace,
              * If we doing COW for this segment then check if the page is
              * already private.
              */
-            if (DoCOW && MmIsPagePresent(Process, Address))
+            if (DoCOW && (MmIsPagePresent(Process, Address) || MmIsDisabledPage(Process, Address)))
             {
                 LARGE_INTEGER Offset;
                 ULONG_PTR Entry;