Re: [PATCH 1/3] MdeModulePkg/MdeModulePkg.dec: add new PCD for UAF detection feature

["Zeng, Star" <star.zeng@intel.com>]

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 <star.zeng@intel.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> ---
>   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
>