From: Peter Jones pjones@redhat.com
Some machines generate a lot of event log entries. When we're iterating over them, the code removes the old mapping and adds a new one, so once we cross the page boundary we're unmapping the page with the count on it. Hilarity ensues.
This patch keeps the info from the header in local variables so we don't need to access that page again or keep track of if it's mapped.
Fixes: 44038bc514a2 ("tpm: Abstract crypto agile event size calculations") Cc: linux-efi@vger.kernel.org Cc: linux-integrity@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Peter Jones pjones@redhat.com Tested-by: Lyude Paul lyude@redhat.com Reviewed-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Acked-by: Matthew Garrett mjg59@google.com Acked-by: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com --- include/linux/tpm_eventlog.h | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h index 63238c84dc0b..12584b69a3f3 100644 --- a/include/linux/tpm_eventlog.h +++ b/include/linux/tpm_eventlog.h @@ -170,6 +170,7 @@ static inline int __calc_tpm2_event_size(struct tcg_pcr_event2_head *event, u16 halg; int i; int j; + u32 count, event_type;
marker = event; marker_start = marker; @@ -190,16 +191,22 @@ static inline int __calc_tpm2_event_size(struct tcg_pcr_event2_head *event, }
event = (struct tcg_pcr_event2_head *)mapping; + /* + * the loop below will unmap these fields if the log is larger than + * one page, so save them here for reference. + */ + count = READ_ONCE(event->count); + event_type = READ_ONCE(event->event_type);
efispecid = (struct tcg_efi_specid_event_head *)event_header->event;
/* Check if event is malformed. */ - if (event->count > efispecid->num_algs) { + if (count > efispecid->num_algs) { size = 0; goto out; }
- for (i = 0; i < event->count; i++) { + for (i = 0; i < count; i++) { halg_size = sizeof(event->digests[i].alg_id);
/* Map the digest's algorithm identifier */ @@ -256,8 +263,9 @@ static inline int __calc_tpm2_event_size(struct tcg_pcr_event2_head *event, + event_field->event_size; size = marker - marker_start;
- if ((event->event_type == 0) && (event_field->event_size == 0)) + if (event_type == 0 && event_field->event_size == 0) size = 0; + out: if (do_mapping) TPM_MEMUNMAP(mapping, mapping_size);