Re: [PATCH v2 05/16] DynamicTablesPkg: Fix Proc node length assignment


Ard Biesheuvel
 

On Sun, 29 Mar 2020 at 17:14, Sami Mujawar <sami.mujawar@arm.com> wrote:

The length field for the Processor Hierarchy node structure is
8-bit wide while the number of private resource field is 32-bit
wide. Therefore, the GetProcHierarchyNodeSize() returns the size
as a 32-bit value.

The VS2017 compiler reports 'warning C4244: '=': conversion from
'UINT32' to 'UINT8', possible loss of data' while assigning the
length field of the Processor Hierarchy node structure.

To fix this, a type cast is added. In addition, there is a check
to ensure that the Processor Hierarchy node size does not exceed
MAX_UINT8.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---

Notes:
v2:
Splitting patch series and re-submitting DynamicTablesPkg [SAMI]
patches from https://edk2.groups.io/g/devel/message/46261

DynamicTablesPkg/Library/Acpi/Arm/AcpiPpttLibArm/PpttGenerator.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/DynamicTablesPkg/Library/Acpi/Arm/AcpiPpttLibArm/PpttGenerator.c b/DynamicTablesPkg/Library/Acpi/Arm/AcpiPpttLibArm/PpttGenerator.c
index 9e42eee9b75bb330833b0f56c98947563d9eb821..40699ce113caa8530c89ac20562cf5abda26b88e 100644
--- a/DynamicTablesPkg/Library/Acpi/Arm/AcpiPpttLibArm/PpttGenerator.c
+++ b/DynamicTablesPkg/Library/Acpi/Arm/AcpiPpttLibArm/PpttGenerator.c
@@ -504,6 +504,7 @@ AddProcHierarchyNodes (

PPTT_NODE_INDEXER * ProcNodeIterator;
UINT32 NodeCount;
+ UINT32 Length;

ASSERT (
(Generator != NULL) &&
@@ -539,8 +540,8 @@ AddProcHierarchyNodes (
// imposed on the Processor Hierarchy node by the specification.
// Note: The length field is 8 bit wide while the number of private
// resource field is 32 bit wide.
- if ((sizeof (EFI_ACPI_6_3_PPTT_STRUCTURE_PROCESSOR) +
- (ProcInfoNode->NoOfPrivateResources * sizeof (UINT32))) > MAX_UINT8) {
+ Length = GetProcHierarchyNodeSize (ProcInfoNode);
+ if (Length > MAX_UINT8) {
Status = EFI_INVALID_PARAMETER;
DEBUG ((
DEBUG_ERROR,
@@ -556,7 +557,7 @@ AddProcHierarchyNodes (

// Populate the node header
ProcStruct->Type = EFI_ACPI_6_3_PPTT_TYPE_PROCESSOR;
- ProcStruct->Length = GetProcHierarchyNodeSize (ProcInfoNode);
+ ProcStruct->Length = (UINT8)Length;
ProcStruct->Reserved[0] = EFI_ACPI_RESERVED_BYTE;
ProcStruct->Reserved[1] = EFI_ACPI_RESERVED_BYTE;

--
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'



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