linux-kernel - Re: [PATCH v3 1/5] tpm: change the end marker of the active

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Date:   Wed, 31 Oct 2018 10:43:00 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Roberto Sassu <roberto.sassu@...wei.com>,
        jarkko.sakkinen@...ux.intel.com
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, silviu.vlasceanu@...wei.com
Subject: Re: [PATCH v3 1/5] tpm: change the end marker of the active_banks
 array to zero

On Tue, 2018-10-30 at 16:47 +0100, Roberto Sassu wrote:
> This patch changes the end marker of the active_banks array from
> TPM2_ALG_ERROR to zero.

The patch description is a bit off.

TPM2_ALG_ERROR is defined as zero.  Since tpm_chip_alloc() calls
kzalloc to allocate the structure, there is no need to explicitly set
the active_banks end marker to TPM2_ALG_ERROR, nor is there a need to
explicitly test for the end marker.

This patch removes explicitly setting the end marker and changes the
coding style.

> 
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> ---
>  drivers/char/tpm/tpm-interface.c | 2 +-
>  drivers/char/tpm/tpm2-cmd.c      | 3 ---
>  2 files changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 1a803b0cf980..f7fc4b5ee239 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -1051,7 +1051,7 @@ int tpm_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
>  		memset(digest_list, 0, sizeof(digest_list));
>  
>  		for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
> -			    chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
> +			    chip->active_banks[i]; i++) {
>  			digest_list[i].alg_id = chip->active_banks[i];
>  			memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
>  			count++;
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index c31b490bd41d..046c9d8f3c1e 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -908,9 +908,6 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
>  	}
>  
>  out:
> -	if (i < ARRAY_SIZE(chip->active_banks))
> -		chip->active_banks[i] = TPM2_ALG_ERROR;
> -
>  	tpm_buf_destroy(&buf);
>  
>  	return rc;