linux-kernel - [PATCH] tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations

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Date:   Mon, 10 Jun 2019 15:01:18 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>
Cc:     groeck@...omium.org, Vadim Sukhomlinov <sukhomlinov@...gle.com>,
        apronin@...omium.org, mka@...omium.org, swboyd@...omium.org,
        Douglas Anderson <dianders@...omium.org>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        Jason Gunthorpe <jgg@...pe.ca>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-integrity@...r.kernel.org
Subject: [PATCH] tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations

From: Vadim Sukhomlinov <sukhomlinov@...gle.com>

TPM 2.0 Shutdown involve sending TPM2_Shutdown to TPM chip and disabling
future TPM operations. TPM 1.2 behavior was different, future TPM
operations weren't disabled, causing rare issues. This patch ensures
that future TPM operations are disabled.

Signed-off-by: Vadim Sukhomlinov <sukhomlinov@...gle.com>
[dianders: resolved merge conflicts with mainline]
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 drivers/char/tpm/tpm-chip.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 8804c9e916fd..f566fa8bf704 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -294,15 +294,15 @@ static int tpm_class_shutdown(struct device *dev)
 {
 	struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
 
+	down_write(&chip->ops_sem);
 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-		down_write(&chip->ops_sem);
 		if (!tpm_chip_start(chip)) {
 			tpm2_shutdown(chip, TPM2_SU_CLEAR);
 			tpm_chip_stop(chip);
 		}
-		chip->ops = NULL;
-		up_write(&chip->ops_sem);
 	}
+	chip->ops = NULL;
+	up_write(&chip->ops_sem);
 
 	return 0;
 }
-- 
2.22.0.rc2.383.gf4fbbf30c2-goog