Re: [PATCH v2] tpm: tpm_ibm_vtpm: Fix unallocated banks

[Stefan Berger <stefanb@linux.ibm.com>]

On 7/6/19 8:18 PM, Nayna Jain wrote:
> The nr_allocated_banks and allocated banks are initialized as part of
> tpm_chip_register. Currently, this is done as part of auto startup
> function. However, some drivers, like the ibm vtpm driver, do not run
> auto startup during initialization. This results in uninitialized memory
> issue and causes a kernel panic during boot.
>
> This patch moves the pcr allocation outside the auto startup function
> into tpm_chip_register. This ensures that allocated banks are initialized
> in any case.
>
> Fixes: 879b589210a9 ("tpm: retrieve digest size of unknown algorithms with
> PCR read")
> Reported-by: Michal Suchanek <msuchanek@suse.de>
> Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
> Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Tested-by: Michal Suchánek <msuchanek@suse.de>
> ---
> Changelog:
>
> v2:
> * Includes Jarkko's feedbacks
>    * fixes the function name to tpm_get_pcr_allocation()
>    * adds new function tpm1_get_pcr_allocation()
>    * updates patch summary line
>    * fixes alignment
>    * adds Reported-by: Michal Suchanek <msuchanek@suse.de>
> * Includes Stefan's feedbacks
>    * Fixes overwriting of return code
>    * Fixes misplacing of tpm_chip_stop()
> * Adds Reviewed-by, Tested-by
>
>   drivers/char/tpm/tpm-chip.c | 22 ++++++++++++++++++++++
>   drivers/char/tpm/tpm.h      |  2 ++
>   drivers/char/tpm/tpm1-cmd.c | 36 ++++++++++++++++++++++++------------
>   drivers/char/tpm/tpm2-cmd.c |  6 +-----
>   4 files changed, 49 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 8804c9e916fd..6589291df355 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -550,6 +550,22 @@ static int tpm_add_hwrng(struct tpm_chip *chip)
>   	return hwrng_register(&chip->hwrng);
>   }
>
> +/*
> + * tpm_get_pcr_allocation() - initialize the chip allocated banks for PCRs
> + * @chip: TPM chip to use.
> + */
> +static int tpm_get_pcr_allocation(struct tpm_chip *chip)
> +{
> +	int rc;
> +
> +	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> +		rc = tpm2_get_pcr_allocation(chip);


For tpm2 case you need:

if (rc > 0)

     rc = -ENODEV;

Because tpm2_get_pcr_allocation(chip) returns ssize_t with return values 
from tpm_transmit_cmd > 0 indicating a TPM 2 error code...


    Stefan