On Sat, Nov 03, 2018 at 02:42:21PM +0800, Jian J Wang wrote:
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1295
>
> This issue originates from following patch which allows to enable
> paging if PcdImageProtectionPolicy and PcdDxeNxMemoryProtectionPolicy
> (in addition to PcdSetNxForStack) are set to enable related features.
>
> 5267926134d17e86672b84fd57b438f05ffa68e1
>
> Due to above change, PcdImageProtectionPolicy will be set to 0 by
> default in many platforms, which, in turn, cause following code in
> MdeModulePkg\Core\Dxe\Misc\MemoryProtection.c fail the creation of
> notify event of CpuArchProtocol.
>
> 1138: if (mImageProtectionPolicy != 0 ||
> PcdGet64 (PcdDxeNxMemoryProtectionPolicy) != 0) {
> 1139: Status = CoreCreateEvent (
> ...
> 1142: MemoryProtectionCpuArchProtocolNotify,
> ...
> 1145: );
>
> Then following call flow won't be done and Guard pages will not be
> set as not-present in SetAllGuardPages() eventually.
>
> MemoryProtectionCpuArchProtocolNotify()
> => HeapGuardCpuArchProtocolNotify()
> => SetAllGuardPages()
>
> The solution is removing the if(...) statement so that the notify
> event will always be created and handler be registered. This won't
> cause unnecessary code execution because, in the notify event handler,
> the related PCDs like
>
> PcdImageProtectionPolicy and
> PcdDxeNxMemoryProtectionPolicy
>
> will be checked again to do its job.
>
> Cc: Star Zeng <star.z...@intel.com>
> Cc: Jiewen Yao <jiewen....@intel.com>
> Cc: Ruiyu Ni <ruiyu...@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.w...@intel.com>
> ---
> MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> index 30e5c5153c..30798b05b9 100644
> --- a/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> +++ b/MdeModulePkg/Core/Dxe/Misc/MemoryProtection.c
> @@ -1135,7 +1135,6 @@ CoreInitializeMemoryProtection (
> ASSERT (GetPermissionAttributeForMemoryType (EfiBootServicesData) ==
> GetPermissionAttributeForMemoryType (EfiConventionalMemory));
>
> - if (mImageProtectionPolicy != 0 || PcdGet64
> (PcdDxeNxMemoryProtectionPolicy) != 0) {
> Status = CoreCreateEvent (
> EVT_NOTIFY_SIGNAL,
> TPL_CALLBACK,
> @@ -1154,7 +1153,6 @@ CoreInitializeMemoryProtection (
> &Registration
> );
> ASSERT_EFI_ERROR(Status);
> - }
And here we see why.
The indentation changes need to be part of this patch, not 1/2.
/
Leif
>
> //
> // Register a callback to disable NULL pointer detection at EndOfDxe
> --
> 2.16.2.windows.1
>
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