As part of the Boothole fixes, shim has introduced an
SBAT feature https://github.com/rhboot/shim/blob/main/SBAT.md.
SBAT configuration is configured to log to PCR7 using
EV_EFI_VARIABLE_AUTHORITY.
493bd940e5/mok.c (L228-L247)
This causes issue with ParseUEFIVariableAuthority, as
it asssumes that an event with type EV_EFI_VARIABLE_AUTHORITY
can be parsed as EFI_SIGNATURE_DATA, per section 3.3.4.8
of the TCG PC Client Platform Firmware Profile Specification.
Found manually looking through the code. The activate credential could
crash the client, the secureboot and challenge generation could crash
the server.
