The following commit has been merged into the efi/urgent branch of tip:

Commit-ID: 05c8c1ff81ed2eb9bad7c27cf92e55c864c16df8 Gitweb: https://git.kernel.org/tip/05c8c1ff81ed2eb9bad7c27cf92e55c864c16df8 Author: Peter Jones pjones@redhat.com AuthorDate: Wed, 02 Oct 2019 18:59:01 +02:00 Committer: Ingo Molnar mingo@kernel.org CommitterDate: Mon, 07 Oct 2019 15:24:35 +02:00

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: c46f3405692d ("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 --- drivers/firmware/efi/tpm.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c index 1d3f5ca..b9ae5c6 100644 --- a/drivers/firmware/efi/tpm.c +++ b/drivers/firmware/efi/tpm.c @@ -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));