MdeModulePkg/Core: fix feature conflict between NX and heap guard

[mirror_edk2.git] / MdeModulePkg / Core / Dxe / Mem / HeapGuard.c

diff --git a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
index bee229f4c8a73b3101b6c2c4e600706c73822766..d7906e08c53c4f795aaf05fe5b0207eb1b1d84e7 100644 (file)
--- a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
+++ b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
@@ -583,8 +583,7 @@ SetGuardPage (
   mOnGuarding = TRUE;\r
   //\r
   // Note: This might overwrite other attributes needed by other features,\r
-  // such as memory protection (NX). Please make sure they are not enabled\r
-  // at the same time.\r
+  // such as NX memory protection.\r
   //\r
   gCpu->SetMemoryAttributes (gCpu, BaseAddress, EFI_PAGE_SIZE, EFI_MEMORY_RP);\r
   mOnGuarding = FALSE;\r
@@ -605,6 +604,18 @@ UnsetGuardPage (
   IN  EFI_PHYSICAL_ADDRESS      BaseAddress\r
   )\r
 {\r
+  UINT64          Attributes;\r
+\r
+  //\r
+  // Once the Guard page is unset, it will be freed back to memory pool. NX\r
+  // memory protection must be restored for this page if NX is enabled for free\r
+  // memory.\r
+  //\r
+  Attributes = 0;\r
+  if ((PcdGet64 (PcdDxeNxMemoryProtectionPolicy) & (1 << EfiConventionalMemory)) != 0) {\r
+    Attributes |= EFI_MEMORY_XP;\r
+  }\r
+\r
   //\r
   // Set flag to make sure allocating memory without GUARD for page table\r
   // operation; otherwise infinite loops could be caused.\r
@@ -615,7 +626,7 @@ UnsetGuardPage (
   // such as memory protection (NX). Please make sure they are not enabled\r
   // at the same time.\r
   //\r
-  gCpu->SetMemoryAttributes (gCpu, BaseAddress, EFI_PAGE_SIZE, 0);\r
+  gCpu->SetMemoryAttributes (gCpu, BaseAddress, EFI_PAGE_SIZE, Attributes);\r
   mOnGuarding = FALSE;\r
 }\r
 \r
@@ -717,6 +728,20 @@ IsPageTypeToGuard (
   return IsMemoryTypeToGuard (MemoryType, AllocateType, GUARD_HEAP_TYPE_PAGE);\r
 }\r
 \r
+/**\r
+  Check to see if the heap guard is enabled for page and/or pool allocation.\r
+\r
+  @return TRUE/FALSE.\r
+**/\r
+BOOLEAN\r
+IsHeapGuardEnabled (\r
+  VOID\r
+  )\r
+{\r
+  return IsMemoryTypeToGuard (EfiMaxMemoryType, AllocateAnyPages,\r
+                              GUARD_HEAP_TYPE_POOL|GUARD_HEAP_TYPE_PAGE);\r
+}\r
+\r
 /**\r
   Set head Guard and tail Guard for the given memory range.\r
 \r
@@ -869,6 +894,15 @@ AdjustMemoryS (
 {\r
   UINT64  Target;\r
 \r
+  //\r
+  // UEFI spec requires that allocated pool must be 8-byte aligned. If it's\r
+  // indicated to put the pool near the Tail Guard, we need extra bytes to\r
+  // make sure alignment of the returned pool address.\r
+  //\r
+  if ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) == 0) {\r
+    SizeRequested = ALIGN_VALUE(SizeRequested, 8);\r
+  }\r
+\r
   Target = Start + Size - SizeRequested;\r
 \r
   //\r
@@ -1052,7 +1086,7 @@ AdjustPoolHeadA (
   IN UINTN                   Size\r
   )\r
 {\r
-  if ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) != 0) {\r
+  if (Memory == 0 || (PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) != 0) {\r
     //\r
     // Pool head is put near the head Guard\r
     //\r
@@ -1062,6 +1096,7 @@ AdjustPoolHeadA (
   //\r
   // Pool head is put near the tail Guard\r
   //\r
+  Size = ALIGN_VALUE (Size, 8);\r
   return (VOID *)(UINTN)(Memory + EFI_PAGES_TO_SIZE (NoPages) - Size);\r
 }\r
 \r
@@ -1077,7 +1112,7 @@ AdjustPoolHeadF (
   IN EFI_PHYSICAL_ADDRESS    Memory\r
   )\r
 {\r
-  if ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) != 0) {\r
+  if (Memory == 0 || (PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) != 0) {\r
     //\r
     // Pool head is put near the head Guard\r
     //\r
@@ -1106,8 +1141,22 @@ CoreConvertPagesWithGuard (
   IN EFI_MEMORY_TYPE  NewType\r
   )\r
 {\r
+  UINT64  OldStart;\r
+  UINTN   OldPages;\r
+\r
   if (NewType == EfiConventionalMemory) {\r
+    OldStart = Start;\r
+    OldPages = NumberOfPages;\r
+\r
     AdjustMemoryF (&Start, &NumberOfPages);\r
+    //\r
+    // It's safe to unset Guard page inside memory lock because there should\r
+    // be no memory allocation occurred in updating memory page attribute at\r
+    // this point. And unsetting Guard page before free will prevent Guard\r
+    // page just freed back to pool from being allocated right away before\r
+    // marking it usable (from non-present to present).\r
+    //\r
+    UnsetGuardForMemory (OldStart, OldPages);\r
     if (NumberOfPages == 0) {\r
       return EFI_SUCCESS;\r
     }\r