Re: [PATCH v3 04/16] tpm: call tpm2_flush_space() on error in tpm_try_transmit()

Jarkko Sakkinen
2018-11-06T05:56:05Z

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@vger.kernel.org
> > Fixes: 745b361e989a ("tpm:tpm: infrastructure for TPM spaces")
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.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