Antonio Alvarez Feijoo
0254e4d66a
Quoting "Trusted Platform Module Library - Part 3: Commands (Rev. 01.59)": "pcrUpdateCounter – this parameter is updated by TPM2_PolicyPCR(). This value may only be set once during a policy. Each time TPM2_PolicyPCR() executes, it checks to see if policySession->pcrUpdateCounter has its default state, indicating that this is the first TPM2_PolicyPCR(). If it has its default value, then policySession->pcrUpdateCounter is set to the current value of pcrUpdateCounter. If policySession->pcrUpdateCounter does not have its default value and its value is not the same as pcrUpdateCounter, the TPM shall return TPM_RC_PCR_CHANGED. If this parameter and pcrUpdateCounter are not the same, it indicates that PCR have changed since checked by the previous TPM2_PolicyPCR(). Since they have changed, the previous PCR validation is no longer valid." The TPM will return TPM_RC_PCR_CHANGED if any PCR value changes (no matter which) between validating the PCRs binded to the enrollment and unsealing the HMAC key, so this patch adds a retry mechanism in this case. Fixes #24906
System and Service Manager
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