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From:   Jerry Snitselaar <jsnitsel@redhat.com>
To:     linux-integrity@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Peter Huewe <peterhuewe@gmx.de>, Jason Gunthorpe <jgg@ziepe.ca>
Subject: [PATCH] tpm_tis: verify locality released before returning from release_locality
Date:   Sat,  5 May 2018 12:54:53 -0700
Message-Id: <20180505195453.10431-1-jsnitsel@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

For certain tpm chips releasing locality can take long enough that a
subsequent call to request_locality will see the locality as being
active when the access register is read in check_locality. So check
that the locality has been released before returning from
release_locality.

Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Peter Huewe <peterhuewe@gmx.de>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Reported-by: Laurent Bigonville <bigon@debian.org>
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
---
 drivers/char/tpm/tpm_tis_core.c | 47 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 5a1f47b43947..d547cd309dbd 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -143,13 +143,58 @@ static bool check_locality(struct tpm_chip *chip, int l)
 	return false;
 }
 
+static bool locality_inactive(struct tpm_chip *chip, int l)
+{
+	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+	int rc;
+	u8 access;
+
+	rc = tpm_tis_read8(priv, TPM_ACCESS(l), &access);
+	if (rc < 0)
+		return false;
+
+	if ((access & (TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY))
+	    == TPM_ACCESS_VALID)
+		return true;
+
+	return false;
+}
+
 static int release_locality(struct tpm_chip *chip, int l)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+	unsigned long stop, timeout;
+	long rc;
 
 	tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
 
-	return 0;
+	stop = jiffies + chip->timeout_a;
+
+	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
+again:
+		timeout = stop - jiffies;
+		if ((long)timeout <= 0)
+			return -1;
+
+		rc = wait_event_interruptible_timeout(priv->int_queue,
+						      (locality_inactive(chip, l)),
+						      timeout);
+
+		if (rc > 0)
+			return 0;
+
+		if (rc == -ERESTARTSYS && freezing(current)) {
+			clear_thread_flag(TIF_SIGPENDING);
+			goto again;
+		}
+	} else {
+		do {
+			if (locality_inactive(chip, l))
+				return 0;
+			tpm_msleep(TPM_TIMEOUT);
+		} while (time_before(jiffies, stop));
+	}
+	return -1;
 }
 
 static int request_locality(struct tpm_chip *chip, int l)
-- 
2.15.0