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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	linux-kernel@vger.kernel.org,
	Ben Dooks <ben.dooks@codethink.co.uk>,
	Dave Young <dyoung@redhat.com>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Jerry Snitselaar <jsnitsel@redhat.com>,
	linux-integrity@vger.kernel.org, Lukas Wunner <lukas@wunner.de>,
	Lyude Paul <lyude@redhat.com>, Matthew Garrett <mjg59@google.com>,
	Octavian Purdila <octavian.purdila@intel.com>,
	Peter Jones <pjones@redhat.com>, Scott Talbert <swt@techie.net>
Subject: [PATCH 4/7] efi/tpm: don't traverse an event log with no events
Date: Wed,  2 Oct 2019 18:59:01 +0200	[thread overview]
Message-ID: <20191002165904.8819-5-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <20191002165904.8819-1-ard.biesheuvel@linaro.org>

From: Peter Jones <pjones@redhat.com>

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.

Fixes: c46f3405692d ("tpm: Reserve the TPM final events table")
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>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.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 1d3f5ca3eaaf..b9ae5c6f9b9c 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));
-- 
2.20.1


  parent reply	other threads:[~2019-10-02 17:04 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-02 16:58 [GIT PULL 0/7] EFI fixes for v5.4 Ard Biesheuvel
2019-10-02 16:58 ` [PATCH 1/7] efi: cper: Fix endianness of PCIe class code Ard Biesheuvel
2019-10-07 14:49   ` [tip: efi/urgent] efi/cper: " tip-bot2 for Lukas Wunner
2019-10-02 16:58 ` [PATCH 2/7] efivar/ssdt: don't iterate over EFI vars if no SSDT override was specified Ard Biesheuvel
2019-10-07 14:49   ` [tip: efi/urgent] efivar/ssdt: Don't " tip-bot2 for Ard Biesheuvel
2019-10-02 16:59 ` [PATCH 3/7] efi/tpm: Don't access event->count when it isn't mapped Ard Biesheuvel
2019-10-07 14:49   ` [tip: efi/urgent] " tip-bot2 for Peter Jones
2019-10-02 16:59 ` Ard Biesheuvel [this message]
2019-10-07 14:49   ` [tip: efi/urgent] efi/tpm: Don't traverse an event log with no events tip-bot2 for Peter Jones
2019-10-02 16:59 ` [PATCH 5/7] efi/tpm: only set efi_tpm_final_log_size after successful event log parsing Ard Biesheuvel
2019-10-07 14:49   ` [tip: efi/urgent] efi/tpm: Only set 'efi_tpm_final_log_size' " tip-bot2 for Jerry Snitselaar
2019-10-02 16:59 ` [PATCH 6/7] efi: make unexported efi_rci2_sysfs_init static Ard Biesheuvel
2019-10-07 14:49   ` [tip: efi/urgent] efi: Make unexported efi_rci2_sysfs_init() static tip-bot2 for Ben Dooks
2019-10-02 16:59 ` [PATCH 7/7] efi/x86: do not clean dummy variable in kexec path Ard Biesheuvel
2019-10-07 14:49   ` [tip: efi/urgent] efi/x86: Do " tip-bot2 for Dave Young

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