On Mon, Mar 13, 2023 at 18:17:08 +0100, Ard Biesheuvel wrote:
> Currently, we invoke ApplyMemoryProtectionPolicy() after
> CoreInternalFreePages() has returned successfully, in order to update
> the memory permission attributes of the region to match the policy for
> EfiConventionalMemory.
>
> There are two problems with that:
> - CoreInternalFreePages() will round up the size of the allocation to
> the appropriate alignment of the memory type, but we only remap the
> number of pages that was passed by the caller, leaving the remaining
> pages freed but mapped with the old permissions;
> - in DEBUG builds, we may attempt to clear the entire region while it is
> still mapped with read-only or read-protect attributes.
>
> Let's address both issues, by updating the permissions before performing
> the actual conversion.
>
> Signed-off-by: Ard Biesheuvel <a...@kernel.org>
> ---
> MdeModulePkg/Core/Dxe/Mem/Page.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c
> b/MdeModulePkg/Core/Dxe/Mem/Page.c
> index 5903ce7ab525..f5b940bbc25b 100644
> --- a/MdeModulePkg/Core/Dxe/Mem/Page.c
> +++ b/MdeModulePkg/Core/Dxe/Mem/Page.c
> @@ -1519,8 +1519,8 @@ CoreAllocatePages (
> @return EFI_SUCCESS -Pages successfully freed.
>
> **/
> +STATIC
> EFI_STATUS
> -EFIAPI
This is addressing a historic oversight (possibly caused by the STATIC
function ban), but it's not *really* related to the change in question.
/
Leif
> CoreInternalFreePages (
> IN EFI_PHYSICAL_ADDRESS Memory,
> IN UINTN NumberOfPages,
> @@ -1574,6 +1574,13 @@ CoreInternalFreePages (
> NumberOfPages += EFI_SIZE_TO_PAGES (Alignment) - 1;
> NumberOfPages &= ~(EFI_SIZE_TO_PAGES (Alignment) - 1);
>
> + ApplyMemoryProtectionPolicy (
> + Entry->Type,
> + EfiConventionalMemory,
> + Memory,
> + EFI_PAGES_TO_SIZE (NumberOfPages)
> + );
> +
> if (MemoryType != NULL) {
> *MemoryType = Entry->Type;
> }
> @@ -1628,12 +1635,6 @@ CoreFreePages (
> NULL
> );
> InstallMemoryAttributesTableOnMemoryAllocation (MemoryType);
> - ApplyMemoryProtectionPolicy (
> - MemoryType,
> - EfiConventionalMemory,
> - Memory,
> - EFI_PAGES_TO_SIZE (NumberOfPages)
> - );
> }
>
> return Status;
> --
> 2.39.2
>
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#101273): https://edk2.groups.io/g/devel/message/101273
Mute This Topic: https://groups.io/mt/97586052/21656
Group Owner: devel+ow...@edk2.groups.io
Unsubscribe:
https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy
[arch...@mail-archive.com]
-=-=-=-=-=-=-=-=-=-=-=-
