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

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Considering following scenario (both NX memory protection and heap guard
are enabled):

   1. Allocate 3 pages. The attributes of adjacent memory pages will be

      |NOT-PRESENT|  present  |  present  |  present  |NOT-PRESENT|

   2. Free the middle page. The attributes of adjacent memory pages should be

      |NOT-PRESENT|  present  |NOT-PRESENT|  present  |NOT-PRESENT|

      But the NX feature will overwrite the attributes of middle page. So it
      looks still like below, which is wrong.

      |NOT-PRESENT|  present  |  PRESENT  |  present  |NOT-PRESENT|

The solution is checking the first and/or last page of a memory block to be
marked as NX, and skipping them if they are Guard pages.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@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>
This commit is contained in:
Jian J Wang
2018-01-29 20:03:33 +08:00
committed by Star Zeng
parent 9b17c6511d
commit a6a0a59756
3 changed files with 46 additions and 0 deletions
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14
MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
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@@ -728,6 +728,20 @@ IsPageTypeToGuard (
return IsMemoryTypeToGuard (MemoryType, AllocateType, GUARD_HEAP_TYPE_PAGE);
}
/**
Check to see if the heap guard is enabled for page and/or pool allocation.
@return TRUE/FALSE.
**/
BOOLEAN
IsHeapGuardEnabled (
VOID
)
{
return IsMemoryTypeToGuard (EfiMaxMemoryType, AllocateAnyPages,
GUARD_HEAP_TYPE_POOL|GUARD_HEAP_TYPE_PAGE);
}
/**
Set head Guard and tail Guard for the given memory range.