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Bug with data marshaling in SecurityPkg/Library/Tpm2CommandLib/Tpm2Integrity.c #5537

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wmjdgla opened this issue Apr 8, 2024 · 1 comment

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@wmjdgla
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wmjdgla commented Apr 8, 2024

Tpm2PcrRead is doing a member-by-member copy of the input TPML_PCR_SELECTION parameter rather than marshaling it:

SendBuffer.PcrSelectionIn.count = SwapBytes32 (PcrSelectionIn->count);
for (Index = 0; Index < PcrSelectionIn->count; Index++) {
SendBuffer.PcrSelectionIn.pcrSelections[Index].hash = SwapBytes16 (PcrSelectionIn->pcrSelections[Index].hash);
SendBuffer.PcrSelectionIn.pcrSelections[Index].sizeofSelect = PcrSelectionIn->pcrSelections[Index].sizeofSelect;
CopyMem (&SendBuffer.PcrSelectionIn.pcrSelections[Index].pcrSelect, &PcrSelectionIn->pcrSelections[Index].pcrSelect, SendBuffer.PcrSelectionIn.pcrSelections[Index].sizeofSelect);
}

This results in the TPM2_PCR_READ_COMMAND bytes being malformed whenever sizeofSelect != PCR_SELECT_MAX.

Further down, Tpm2PcrAllocate also marshals an input TPML_PCR_SELECTION parameter and it is done correctly:

WriteUnaligned32 ((UINT32 *)Buffer, SwapBytes32 (PcrAllocation->count));
Buffer += sizeof (UINT32);
for (Index = 0; Index < PcrAllocation->count; Index++) {
WriteUnaligned16 ((UINT16 *)Buffer, SwapBytes16 (PcrAllocation->pcrSelections[Index].hash));
Buffer += sizeof (UINT16);
*(UINT8 *)Buffer = PcrAllocation->pcrSelections[Index].sizeofSelect;
Buffer++;
CopyMem (Buffer, PcrAllocation->pcrSelections[Index].pcrSelect, PcrAllocation->pcrSelections[Index].sizeofSelect);
Buffer += PcrAllocation->pcrSelections[Index].sizeofSelect;
}

@jyao1
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jyao1 commented Jun 28, 2024

Yes, agree this is a bug. Do you want to propose a patch?

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