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>
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