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

Commit-ID: e658c82be5561412c5e83b5e74e9da4830593f3e Gitweb: https://git.kernel.org/tip/e658c82be5561412c5e83b5e74e9da4830593f3e Author: Jerry Snitselaar jsnitsel@redhat.com AuthorDate: Wed, 02 Oct 2019 18:59:02 +02:00 Committer: Ingo Molnar mingo@kernel.org CommitterDate: Mon, 07 Oct 2019 15:24:36 +02:00

efi/tpm: Only set 'efi_tpm_final_log_size' after successful event log parsing

If __calc_tpm2_event_size() fails to parse an event it will return 0, resulting tpm2_calc_event_log_size() returning -1. Currently there is no check of this return value, and 'efi_tpm_final_log_size' can end up being set to this negative value resulting in a crash like this one:

BUG: unable to handle page fault for address: ffffbc8fc00866ad #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page

RIP: 0010:memcpy_erms+0x6/0x10 Call Trace: tpm_read_log_efi() tpm_bios_log_setup() tpm_chip_register() tpm_tis_core_init.cold.9+0x28c/0x466 tpm_tis_plat_probe() platform_drv_probe() ...

Also __calc_tpm2_event_size() returns a size of 0 when it fails to parse an event, so update function documentation to reflect this.

The root cause of the issue that caused the failure of event parsing in this case is resolved by Peter Jone's patchset dealing with large event logs where crossing over a page boundary causes the page with the event count to be unmapped.

Signed-off-by: Jerry Snitselaar jsnitsel@redhat.com Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org Cc: Ben Dooks ben.dooks@codethink.co.uk Cc: Dave Young dyoung@redhat.com Cc: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Lukas Wunner lukas@wunner.de Cc: Lyude Paul lyude@redhat.com Cc: Matthew Garrett mjg59@google.com Cc: Octavian Purdila octavian.purdila@intel.com Cc: Peter Jones pjones@redhat.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: c46f3405692de ("tpm: Reserve the TPM final events table") Link: https://lkml.kernel.org/r/20191002165904.8819-6-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar mingo@kernel.org --- drivers/firmware/efi/tpm.c | 9 ++++++++- include/linux/tpm_eventlog.h | 2 +- 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c index b9ae5c6..703469c 100644 --- a/drivers/firmware/efi/tpm.c +++ b/drivers/firmware/efi/tpm.c @@ -85,11 +85,18 @@ int __init efi_tpm_eventlog_init(void) final_tbl->nr_events, log_tbl->log); } + + if (tbl_size < 0) { + pr_err(FW_BUG "Failed to parse event in TPM Final Events Log\n"); + goto out_calc; + } + memblock_reserve((unsigned long)final_tbl, tbl_size + sizeof(*final_tbl)); - early_memunmap(final_tbl, sizeof(*final_tbl)); efi_tpm_final_log_size = tbl_size;

+out_calc: + early_memunmap(final_tbl, sizeof(*final_tbl)); out: early_memunmap(log_tbl, sizeof(*log_tbl)); return ret; diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h index b50cc3a..131ea1b 100644 --- a/include/linux/tpm_eventlog.h +++ b/include/linux/tpm_eventlog.h @@ -152,7 +152,7 @@ struct tcg_algorithm_info { * total. Once we've done this we know the offset of the data length field, * and can calculate the total size of the event. * - * Return: size of the event on success, <0 on failure + * Return: size of the event on success, 0 on failure */

static inline int __calc_tpm2_event_size(struct tcg_pcr_event2_head *event,