Re: [PATCH] tpm: Fix expected number of response bytes of TPM1.2 PCR Extend

Jarkko Sakkinen
2017-02-15T18:09:08Z

On Wed, Feb 15, 2017 at 11:56:23AM -0500, Stefan Berger wrote:
> The TPM1.2 PCR Extend operation only returns 20 bytes in the body,
> which is the size of the PCR state.
>
> This fixes a problem where IMA gets errors with every PCR Extend.
>
> Fixes: c659af78eb7b ("tpm: Check size of response before accessing data")
> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> Acked-by: Mimi Zohar <zohar@us.ibm.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

/Jarkko

> ---
> drivers/char/tpm/tpm-interface.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 6e368ee..bd2128e 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -767,7 +767,7 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read);
>
> #define TPM_ORD_PCR_EXTEND cpu_to_be32(20)
> #define EXTEND_PCR_RESULT_SIZE 34
> -#define EXTEND_PCR_RESULT_BODY_SIZE 24
> +#define EXTEND_PCR_RESULT_BODY_SIZE 20
> static const struct tpm_input_header pcrextend_header = {
> .tag = TPM_TAG_RQU_COMMAND,
> .length = cpu_to_be32(34),
> --
> 2.4.3
>