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

1 files changed, 1 insertions, 1 deletions

diff --git a/tpm.c b/tpm.c
index 516fb876..c0617bb4 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)
 {