Commit 05c8c1ff authored by Peter Jones's avatar Peter Jones Committed by Ingo Molnar
Browse files

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: default avatarLyude Paul <lyude@redhat.com>
Signed-off-by: default avatarPeter Jones <pjones@redhat.com>
Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Acked-by: default avatarMatthew Garrett <mjg59@google.com>
Acked-by: default avatarArd 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: c46f3405 ("tpm: Reserve the TPM final events table")
Link: https://lkml.kernel.org/r/20191002165904.8819-5-ard.biesheuvel@linaro.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 047d50ae

drivers/firmware/efi/tpm.c

+10 −5
Original line number Diff line number Diff line
@@ -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

	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),

				+ 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));