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authorPeter Jones <pjones@redhat.com>2019-10-02 18:59:00 +0200
committerIngo Molnar <mingo@kernel.org>2019-10-07 15:24:35 +0200
commit047d50aee341d940350897c85799e56ae57c3849 (patch)
treee680a4d259a2b32a78e427db1b9712521dd663b7
parentc05f8f92b701576b615f30aac31fabdc0648649b (diff)
efi/tpm: Don't access event->count when it isn't mapped
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. 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: 44038bc514a2 ("tpm: Abstract crypto agile event size calculations") Link: https://lkml.kernel.org/r/20191002165904.8819-4-ard.biesheuvel@linaro.org [ Minor edits. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--include/linux/tpm_eventlog.h14
1 files changed, 11 insertions, 3 deletions
diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h
index 63238c84dc0b..b50cc3adca18 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);