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

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Message-ID: <b2622675-041b-c1af-4670-aecab2adf3ac@huawei.com>
Date:   Mon, 5 Nov 2018 09:10:58 +0100
From:   Roberto Sassu <roberto.sassu@...wei.com>
To:     Mimi Zohar <zohar@...ux.ibm.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 11/1/2018 3:42 PM, Mimi Zohar wrote:
> On Wed, 2018-10-31 at 10:43 -0400, Mimi Zohar wrote:
>> 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++;
> 
> The fourth patch further updates this code.  Please move those changes
> to this first patch.  No need to touch the same code in both places.

alg_id is introduced in patch 4/5. It cannot be moved here.

Roberto


>                  for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
> -                           chip->active_banks[i]; i++) {
> -                       digest_list[i].alg_id = chip->active_banks[i];
> +                           chip->active_banks[i].alg_id; i++) {
> +                       digest_list[i].alg_id = chip->active_banks[i].alg_id;
>                          memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
>                          count++;
>                  }
> Mimi
> 
>>> 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;
>>
> 

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