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:

quoted

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

quoted

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 <redacted>
---
  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