From 9f80be9f16a854e3946568fa92edebe26eb79e78 Mon Sep 17 00:00:00 2001

From: Chris Coulson <chris.coulson@canonical.com>

Date: Sat, 22 Jun 2019 15:37:29 +0100

Subject: [PATCH 38/62] tpm: Define EFI_VARIABLE_DATA_TREE as packed

tpm_measure_variable() calculates VarLogSize by adding the size of VarName

and VarData to the size of EFI_VARIABLE_DATA_TREE, and then subtracting

the size of the UnicodeName and VariableData members. This results in a

calculation that is 5 bytes larger than necessary because it doesn't take

in to account the padding of these members. The effect of this is that

shim measures an additional 5 zero bytes when measuring UEFI variables

(at least on 64-bit architectures).

Byte packing EFI_VARIABLE_DATA_TREE fixes this.

Upstream-commit-id: 7e4d3f1c8c7

---

 tpm.c | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tpm.c b/tpm.c

index 516fb876caa..c0617bb479e 100644

--- a/tpm.c

+++ b/tpm.c

@@ -233,7 +233,7 @@ typedef struct {

 	UINT64 VariableDataLength;

 	CHAR16 UnicodeName[1];

 	INT8 VariableData[1];

-} EFI_VARIABLE_DATA_TREE;

+} __attribute__ ((packed)) EFI_VARIABLE_DATA_TREE;

 static BOOLEAN tpm_data_measured(CHAR16 *VarName, EFI_GUID VendorGuid, UINTN VarSize, VOID *VarData)

 {

-- 

2.26.2