linux-kernel - Re: [PATCH v3 03/16] tpm: return 0 from pcrs_show() when tpm1_pcr

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Message-ID: <20181106055424.GC15575@linux.intel.com>
Date:   Tue, 6 Nov 2018 07:54:24 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Tomas Winkler <tomas.winkler@...el.com>,
        Tadeusz Struk <tadeusz.struk@...el.com>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 03/16] tpm: return 0 from pcrs_show() when
 tpm1_pcr_read() fails

On Mon, Nov 05, 2018 at 04:54:52PM -0500, Stefan Berger wrote:
> On 11/4/18 8:45 PM, Jarkko Sakkinen wrote:
> > Do not print partial list of PCRs when tpm1_pcr_read() fails but instead
> > return 0 from pcrs_show(). This is consistent behavior with other sysfs
> > functions.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > ---
> >   drivers/char/tpm/tpm-sysfs.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
> > index 7ed7eb6f906a..d3b05c7526c8 100644
> > --- a/drivers/char/tpm/tpm-sysfs.c
> > +++ b/drivers/char/tpm/tpm-sysfs.c
> > @@ -115,13 +115,15 @@ static ssize_t pcrs_show(struct device *dev, struct device_attribute *attr,
> >   	for (i = 0; i < num_pcrs; i++) {
> >   		rc = tpm1_pcr_read(chip, i, digest);
> >   		if (rc)
> > -			break;
> > +			goto out;
> 
> Previous patch said "Return zero when tpm_buf_init() fails as we do for
> other functions in tpm-sysfs.c.". Why not return 0 in this case as well?

Yes, good catch, thank you.

/Jarkko