On Fri, Jan 04, 2019 at 07:04:32PM +0100, Ard Biesheuvel wrote:
> PopulateLevel2PageTable () is invoked for [parts of] mappings that
> start or end on a non-1 MB aligned address (or both). The size of
> the mapping depends on both the start address modulo 1 MB and the
> length of the mapping, but the logic that calculates this size is
> flawed: subtracting 'start address modulo 1 MB' could result in a
> negative value for the remaining length, which is obviously wrong.
>
> So instead, take either RemainLength, or the rest of the 1 MB
> block, whichever is smaller.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindh...@linaro.org>
> ---
> ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
> b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
> index b237321a8d8b..3b3b20aa9b78 100644
> --- a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
> +++ b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
> @@ -294,8 +294,8 @@ FillTranslationTable (
> PhysicalBase += TT_DESCRIPTOR_SECTION_SIZE;
> RemainLength -= TT_DESCRIPTOR_SECTION_SIZE;
> } else {
> - PageMapLength = MIN (RemainLength, TT_DESCRIPTOR_SECTION_SIZE) -
> - (PhysicalBase % TT_DESCRIPTOR_SECTION_SIZE);
> + PageMapLength = MIN (RemainLength, TT_DESCRIPTOR_SECTION_SIZE -
> + (PhysicalBase %
> TT_DESCRIPTOR_SECTION_SIZE));
>
> // Case: Physical address aligned on the Section Size (1MB) && the
> length
> // does not fill a section
> --
> 2.17.1
>
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