On 2018/10/19 9:50, Jian J Wang wrote:
UAF (Use-After-Free) memory detection is new feature introduced to
detect illegal access to memory which has been freed. The principle
behind is similar to heap guard feature, that is we'll turn all pool
memory allocation to page allocation and mark them to be not-present
once they are freed.
This also implies that, once a page is allocated and freed, it cannot
be re-allocated. This will bring another issue, which is that there's
risk that memory space will be used out. To address it, this patch
series add logic put part (at most 64 pages a time) of freed pages
back into page pool, so that the memory service can still have memory
to allocate, when all memory space have been allocated once. This is
called memory promotion. The promoted pages are always from the eldest
pages freed.
To use this feature, one can simply set following PCD to 1
gEfiMdeModulePkgTokenSpaceGuid.PcdUseAfterFreeDetectionPropertyMask
Please note this feature cannot be used with heap guard feature controlled
by PCD gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPropertyMask.
How about adding this sentence into the description of
PcdUseAfterFreeDetectionPropertyMask, and correspondingly adding some
information in the description of PcdHeapGuardPropertyMask?
Cc: Star Zeng <[email protected]>
Cc: Michael D Kinney <[email protected]>
Cc: Jiewen Yao <[email protected]>
Cc: Ruiyu Ni <[email protected]>
Cc: Laszlo Ersek <[email protected]>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <[email protected]>
---
MdeModulePkg/MdeModulePkg.dec | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 6037504fa7..83736cd761 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -1029,6 +1029,12 @@
# @Prompt Enable UEFI Stack Guard.
gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard|FALSE|BOOLEAN|0x30001055
+ ## This mask is to control Use-After-Free Memory Detection behavior.
+ # BIT0 - Enable Use-After-Free memory detection for UEFI modules.<BR>
+ # BIT1..7 - Reserved for future uses.<BR>
+ # @Prompt The Use-After-Free Memory Detection feature mask
+
gEfiMdeModulePkgTokenSpaceGuid.PcdUseAfterFreeDetectionPropertyMask|0x0|UINT8|0x30001056
Remember to update MdeModulePkg.uni for it.
Thanks,
Star
+
[PcdsFixedAtBuild, PcdsPatchableInModule]
## Dynamic type PCD can be registered callback function for Pcd setting
action.
# PcdMaxPeiPcdCallBackNumberPerPcdEntry indicates the maximum number of
callback function
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