Re: [PATCH V2 2/2] tpm: Don't duplicate events from the final event log in the TCG2 log

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

On Fri, Jun 07, 2019 at 01:51:47PM -0700, Matthew Garrett wrote:
> After the first call to GetEventLog() on UEFI systems using the TCG2
> crypto agile log format, any further log events (other than those
> triggered by ExitBootServices()) will be logged in both the main log and
> also in the Final Events Log. While the kernel only calls GetEventLog()
> immediately before ExitBootServices(), we can't control whether earlier
> parts of the boot process have done so. This will result in log entries
> that exist in both logs, and so the current approach of simply appending
> the Final Event Log to the main log will result in events being
> duplicated.
> 
> We can avoid this problem by looking at the size of the Final Event Log
> just before we call ExitBootServices() and exporting this to the main
> kernel. The kernel can then skip over all events that occured before
> ExitBootServices() and only append events that were not also logged to
> the main log.
> 
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Reported-by: Joe Richey <joerichey@google.com>
> Suggested-by: Joe Richey <joerichey@google.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

/Jarkko