[edk2-devel] [PATCH v3] EmbeddedPkg/PrePiMemoryAllocationLib: Add check for space on offset allocation

[Jeff Brasen via groups.io]

Update check for enough space to occur prior to alignment offset.

This prevents cases where EfiFreeMemoryTop < EfiFreeMemoryBottom.



Change-Id: I58c5d378523c881a4afc655e7ace4c009130c781

---

 .../MemoryAllocationLib.c                     | 48 ++++++++-----------

 1 file changed, 21 insertions(+), 27 deletions(-)



diff --git a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c

index 2cc2a71121..08a0add340 100644

--- a/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c

+++ b/EmbeddedPkg/Library/PrePiMemoryAllocationLib/MemoryAllocationLib.c

@@ -23,41 +23,35 @@ InternalAllocatePages (

   )

 {

   EFI_PEI_HOB_POINTERS  Hob;

-  EFI_PHYSICAL_ADDRESS  Offset;

+  EFI_PHYSICAL_ADDRESS  NewTop;

 

   Hob.Raw = GetHobList ();

 

-  // Check to see if on 4k boundary

-  Offset = Hob.HandoffInformationTable->EfiFreeMemoryTop & 0xFFF;

-  if (Offset != 0) {

-    // If not aligned, make the allocation aligned.

-    Hob.HandoffInformationTable->EfiFreeMemoryTop -= Offset;

-  }

+  NewTop  = Hob.HandoffInformationTable->EfiFreeMemoryTop & ~(EFI_PHYSICAL_ADDRESS)EFI_PAGE_MASK;

+  NewTop -= Pages * EFI_PAGE_SIZE;

 

   //

   // Verify that there is sufficient memory to satisfy the allocation

   //

-  if (Hob.HandoffInformationTable->EfiFreeMemoryTop - ((Pages * EFI_PAGE_SIZE) + sizeof (EFI_HOB_MEMORY_ALLOCATION)) < Hob.HandoffInformationTable->EfiFreeMemoryBottom) {

-    return 0;

-  } else {

-    //

-    // Update the PHIT to reflect the memory usage

-    //

-    Hob.HandoffInformationTable->EfiFreeMemoryTop -= Pages * EFI_PAGE_SIZE;

-

-    // This routine used to create a memory allocation HOB a la PEI, but that's not

-    // necessary for us.

-

-    //

-    // Create a memory allocation HOB.

-    //

-    BuildMemoryAllocationHob (

-      Hob.HandoffInformationTable->EfiFreeMemoryTop,

-      Pages * EFI_PAGE_SIZE,

-      MemoryType

-      );

-    return (VOID *)(UINTN)Hob.HandoffInformationTable->EfiFreeMemoryTop;

+  if (NewTop < (Hob.HandoffInformationTable->EfiFreeMemoryBottom + sizeof (EFI_HOB_MEMORY_ALLOCATION))) {

+    return NULL;

   }

+

+  //

+  // Update the PHIT to reflect the memory usage

+  //

+  Hob.HandoffInformationTable->EfiFreeMemoryTop = NewTop;

+

+  //

+  // Create a memory allocation HOB.

+  //

+  BuildMemoryAllocationHob (

+    Hob.HandoffInformationTable->EfiFreeMemoryTop,

+    Pages * EFI_PAGE_SIZE,

+    MemoryType

+    );

+

+  return (VOID *)(UINTN)Hob.HandoffInformationTable->EfiFreeMemoryTop;

 }

 

 /**

-- 

2.25.1





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