Re: [PATCH v2 2/2] tests: Skip over pcrUpdateCounter byte in result comparison

[David Gibson]

On Tue, Jul 07, 2020 at 12:05:22AM -0400, Stefan Berger wrote:
> Due to a change in the TPM 2 code the pcrUpdate counter in the
> PCRRead response is now different, so we skip comparison of the
> 14th byte.

Can you elaborate on this a bit, both in the code comment and the
commit message.

> 
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> ---
>  tests/qtest/tpm-util.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/qtest/tpm-util.c b/tests/qtest/tpm-util.c
> index 34efae8f18..58a9593745 100644
> --- a/tests/qtest/tpm-util.c
> +++ b/tests/qtest/tpm-util.c
> @@ -139,7 +139,11 @@ void tpm_util_pcrread(QTestState *s, tx_func *tx,
>  
>      tx(s, tpm_pcrread, sizeof(tpm_pcrread), buffer, sizeof(buffer));
>  
> -    g_assert_cmpmem(buffer, exp_resp_size, exp_resp, exp_resp_size);
> +    /* skip pcrUpdateCounter (14th byte) in comparison */
> +    g_assert(exp_resp_size >= 15);
> +    g_assert_cmpmem(buffer, 13, exp_resp, 13);
> +    g_assert_cmpmem(&buffer[14], exp_resp_size - 14,
> +                    &exp_resp[14], exp_resp_size - 14);
>  }
>  
>  bool tpm_util_swtpm_has_tpm2(void)

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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