linux-kernel - Re: [PATCH v3 04/16] tpm: call tpm2_flush_space() on error in tpm_try

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Date:   Tue, 6 Nov 2018 07:55:54 +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>, stable@...r.kernel.org,
        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 04/16] tpm: call tpm2_flush_space() on error in
 tpm_try_transmit()

On Mon, Nov 05, 2018 at 05:01:46PM -0500, Stefan Berger wrote:
> On 11/4/18 8:45 PM, Jarkko Sakkinen wrote:
> > Always call tpm2_flush_space() on failure in tpm_try_transmit() so that
> > the volatile memory of the TPM gets cleared. If /dev/tpm0 does not have
> > sufficient permissions (usually it has), this could leak to the leakage
> 
> leak ->lead
> 
> 
> > of TPM objects. Through /dev/tpmrm0 this issue does not raise new
> > security concerns.
> > 
> > Cc: stable@...r.kernel.org
> > Fixes: 745b361e989a ("tpm:tpm: infrastructure for TPM spaces")
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > ---
> >   drivers/char/tpm/tpm-interface.c | 28 +++++++++++++++++-----------
> >   drivers/char/tpm/tpm.h           |  1 +
> >   drivers/char/tpm/tpm2-space.c    |  2 +-
> >   3 files changed, 19 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> > index 64510ed81b46..ecda6f96cde0 100644
> > --- a/drivers/char/tpm/tpm-interface.c
> > +++ b/drivers/char/tpm/tpm-interface.c
> > @@ -224,14 +224,14 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> > 
> >   	rc = tpm2_prepare_space(chip, space, ordinal, buf);
> >   	if (rc)
> > -		goto out;
> > +		goto out_idle;
> > 
> >   	rc = chip->ops->send(chip, buf, count);
> >   	if (rc < 0) {
> >   		if (rc != -EPIPE)
> >   			dev_err(&chip->dev,
> >   				"%s: tpm_send: error %d\n", __func__, rc);
> > -		goto out;
> > +		goto out_space;
> >   	}
> > 
> >   	if (chip->flags & TPM_CHIP_FLAG_IRQ)
> > @@ -247,7 +247,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> >   		if (chip->ops->req_canceled(chip, status)) {
> >   			dev_err(&chip->dev, "Operation Canceled\n");
> >   			rc = -ECANCELED;
> > -			goto out;
> > +			goto out_space;
> >   		}
> > 
> >   		tpm_msleep(TPM_TIMEOUT_POLL);
> > @@ -257,7 +257,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> >   	chip->ops->cancel(chip);
> >   	dev_err(&chip->dev, "Operation Timed out\n");
> >   	rc = -ETIME;
> > -	goto out;
> > +	goto out_space;
> > 
> >   out_recv:
> >   	len = chip->ops->recv(chip, buf, bufsiz);
> > @@ -265,22 +265,28 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> >   		rc = len;
> >   		dev_err(&chip->dev,
> >   			"tpm_transmit: tpm_recv: error %d\n", rc);
> > -		goto out;
> > +		goto out_idle;
> 
> Why not jump to out_space here and in 2 instances below?

Ugh, should (and meant) to be like that. Thanks!

/Jarkko