[PATCH v5 6/7] tpm: ensure that the output of PCR read contains the correct digest size

[Roberto Sassu]

On 11/18/2018 8:32 AM, Jarkko Sakkinen wrote:
> On Fri, Nov 16, 2018 at 05:06:48PM +0100, Roberto Sassu wrote:
>> On 11/16/2018 2:41 PM, Jarkko Sakkinen wrote:
>>> On Wed, Nov 14, 2018 at 04:31:07PM +0100, Roberto Sassu wrote:
>>>> This patch protects against data corruption that could happen in the bus,
>>>> by checking that that the digest size returned by the TPM during a PCR read
>>>> matches the size of the algorithm passed to tpm2_pcr_read().
>>>>
>>>> This check is performed after information about the PCR banks has been
>>>> retrieved.
>>>>
>>>> Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>
>>>> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen at linux.intel.com>
>>>> Cc: stable at vger.kernel.org
>>>
>>> Missing fixes tag.
>>
>> Before this patch set, tpm2_pcr_extend() always copied 20 bytes from the
>> output sent by the TPM.
>>
>> Roberto
> 
> Aah, right, of course. Well the patch set is ATM somewhat broken because
> this would require a fixes tag that points to a patch insdie the patch
> set.
> 
> Probably good way to fix the issue is to just merge this with the
> earlier commit.

Unfortunately, it is not possible. The exact digest size has been
introduced with patch 5/7.

Roberto


> /Jarkko
> 

-- 
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Bo PENG, Jian LI, Yanli SHI