efi/tpm: Don't traverse an event log with no events

When there are no entries to put into the final event log, some machines
will return the template they would have populated anyway.  In this case
the nr_events field is 0, but the rest of the log is just garbage.

This patch stops us from trying to iterate the table with
__calc_tpm2_event_size() when the number of events in the table is 0.

Tested-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Acked-by: Matthew Garrett <mjg59@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: Dave Young <dyoung@redhat.com>
Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Octavian Purdila <octavian.purdila@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Talbert <swt@techie.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Cc: linux-integrity@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: c46f340569 ("tpm: Reserve the TPM final events table")
Link: https://lkml.kernel.org/r/20191002165904.8819-5-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Jones 2019-10-02 18:59:01 +02:00 коммит произвёл Ingo Molnar
Родитель 047d50aee3
Коммит 05c8c1ff81
1 изменённых файлов: 10 добавлений и 5 удалений

Просмотреть файл

@ -75,11 +75,16 @@ int __init efi_tpm_eventlog_init(void)
goto out;
}
tbl_size = tpm2_calc_event_log_size((void *)efi.tpm_final_log
+ sizeof(final_tbl->version)
+ sizeof(final_tbl->nr_events),
final_tbl->nr_events,
log_tbl->log);
tbl_size = 0;
if (final_tbl->nr_events != 0) {
void *events = (void *)efi.tpm_final_log
+ sizeof(final_tbl->version)
+ sizeof(final_tbl->nr_events);
tbl_size = tpm2_calc_event_log_size(events,
final_tbl->nr_events,
log_tbl->log);
}
memblock_reserve((unsigned long)final_tbl,
tbl_size + sizeof(*final_tbl));
early_memunmap(final_tbl, sizeof(*final_tbl));