Re: [PATCH] tpm: vtpm_proxy: Do not access host's event log

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On 11/17/2016 03:37 PM, Jarkko Sakkinen wrote:
On Thu, Nov 17, 2016 at 07:35:05AM -0500, Stefan Berger wrote:
On 11/16/2016 03:07 PM, Jason Gunthorpe wrote:
On Wed, Nov 16, 2016 at 12:07:23PM -0500, Stefan Berger wrote:
The culprit seems to be 'tpm: fix the missing .owner in
tpm_bios_measurements_ops'
That is unlikely, it is probably the patch before which calls read_log
unconditionally now. That suggests the crashing is a little random..
I ran the vtpm driver test suite (with -j32) a few times at that patch and
it didn't crash. It crashes severely with later patches applied. Here's the
current experimental patch that fixes these problems:

iff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
index 0cb43ef..a73295a 100644
--- a/drivers/char/tpm/tpm_acpi.c
+++ b/drivers/char/tpm/tpm_acpi.c
@@ -56,6 +56,9 @@ int tpm_read_log_acpi(struct tpm_chip *chip)

      log = &chip->log;

+    if (!chip->acpi_dev_handle)
+        return 0;
+
If there is a problem in the TPM driver, this does not fix the
problem. It will mask the problem. Maybe there's an ACPI regression
in the rc tree?

Following the path from here :

http://lxr.free-electrons.com/source/drivers/acpi/acpica/tbxface.c#L282

acpi_get_table_with_size -> acpi_tb_validate_table -> acpi_tb_acquire_table

I see acpi_os_map_memory being called in acpi_tb_acquire_table but not the corresponding acpi_os_unmap_memory...

    Stefan



This is a funky situation because those lines need to be there but
I do not want them before it is root caused that it is not a TPM
bug.

/Jarkko


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