Commit 05c8c1ff authored Oct 02, 2019 by Peter Jones Committed by Ingo Molnar Oct 07, 2019

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: c46f3405 ("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>

parent 047d50ae

drivers/firmware/efi/tpm.c

+10 −5

Original line number	Original line	Diff line number	Diff line
	@@ -75,11 +75,16 @@ int __init efi_tpm_eventlog_init(void)
	goto out;		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->version)
	+ sizeof(final_tbl->nr_events),		+ sizeof(final_tbl->nr_events);

			tbl_size = tpm2_calc_event_log_size(events,
	final_tbl->nr_events,		final_tbl->nr_events,
	log_tbl->log);		log_tbl->log);
			}
	memblock_reserve((unsigned long)final_tbl,		memblock_reserve((unsigned long)final_tbl,
	tbl_size + sizeof(*final_tbl));		tbl_size + sizeof(*final_tbl));
	early_memunmap(final_tbl, sizeof(*final_tbl));		early_memunmap(final_tbl, sizeof(*final_tbl));

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