linux-kernel - Re: [PATCH v11 00/16] Remove nested TPM operations

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Message-ID: <20190208131231.GB16679@linux.intel.com>
Date:   Fri, 8 Feb 2019 15:12:31 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>
Cc:     Alexander Steffen <Alexander.Steffen@...ineon.com>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Peter Huewe <PeterHuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>,
        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>
Subject: Re: [PATCH v11 00/16] Remove nested TPM operations

On Fri, Feb 08, 2019 at 07:22:48AM -0500, Stefan Berger wrote:
> On 2/8/19 6:50 AM, Jarkko Sakkinen wrote:
> > On Thu, Feb 07, 2019 at 09:14:54PM -0500, Stefan Berger wrote:
> > 
> > >       chip->ops = NULL;
> > >       up_write(&chip->ops_sem);
> > >   }
> > > diff --git a/drivers/char/tpm/tpm-interface.c
> > > b/drivers/char/tpm/tpm-interface.c
> > > index 02e8cffd1163..fcd845ad8c3c 100644
> > > --- a/drivers/char/tpm/tpm-interface.c
> > > +++ b/drivers/char/tpm/tpm-interface.c
> > > @@ -124,6 +124,8 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> > > void *buf, size_t bufsiz)
> > >           dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
> > >       } else if (len < TPM_HEADER_SIZE || len != be32_to_cpu(header->length))
> > >           rc = -EFAULT;
> > > +    else
> > > +        rc = 0;
> > Why is this needed?
> 
> Because it holds a non-zero value, which is wrong at this point. Below it
> is:
> 
> return rc ? rc : len;
> 
> It will always return that rc and never 'len'.
> 
> It's not just needed for bisecting. I still need it with your latest tree.
> That's the only change I need with my current testing of tpm_vtpm_proxy, TIS
> + TPM 1.2 , TIS + TPM 2.0 , and CRB + TPM 2.0 (with QEMU :-) ).

The code is unchaged. If there was a regression that would have been
ages.

/Jarkko