linux-kernel - [PATCH v2] tpm: Fix the driver cleanup code

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Date:   Thu, 21 Dec 2017 15:13:39 -0800
From:   Azhar Shaikh <azhar.shaikh@...el.com>
To:     jarkko.sakkinen@...ux.intel.com, jgg@...pe.ca, javierm@...hat.com,
        peterhuewe@....de
Cc:     linux-security-module@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        azhar.shaikh@...el.com
Subject: [PATCH v2] tpm: Fix the driver cleanup code

Commit 3c1701339284353c41 ("tpm: Keep CLKRUN enabled throughout
the duration of transmit_cmd()") added code which accessed
chip->ops, even after it was set to NULL in tpm_del_char_device(),
called from tpm_chip_unregister() in error / driver exit paths.
So fix this code.

Fixes: 3c1701339284353c41 ("tpm: Keep CLKRUN enabled throughout
the duration of transmit_cmd()")

Suggested-by: Javier Martinez Canillas <javierm@...hat.com>
Suggested-by: Jason Gunthorpe <jgg@...pe.ca>
Signed-off-by: Azhar Shaikh <azhar.shaikh@...el.com>
---
Changes in v2:
- Remove TPM_CHIP_FLAG_DO_NOT_CLEAR_OPS flag, instead call
  tpm_tis_clkrun_enable() directly in tpm_tis_remove()
- Add comment to tpm_tis_clkrun_enable()

 drivers/char/tpm/tpm_tis.c      |  6 ------
 drivers/char/tpm/tpm_tis_core.c | 29 +++++++++++++++++------------
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
index d29add49b033..c847fc69a2fc 100644
--- a/drivers/char/tpm/tpm_tis.c
+++ b/drivers/char/tpm/tpm_tis.c
@@ -275,9 +275,6 @@ static void tpm_tis_pnp_remove(struct pnp_dev *dev)
 
 	tpm_chip_unregister(chip);
 	tpm_tis_remove(chip);
-	if (is_bsw())
-		iounmap(priv->ilb_base_addr);
-
 }
 
 static struct pnp_driver tis_pnp_driver = {
@@ -329,9 +326,6 @@ static int tpm_tis_plat_remove(struct platform_device *pdev)
 	tpm_chip_unregister(chip);
 	tpm_tis_remove(chip);
 
-	if (is_bsw())
-		iounmap(priv->ilb_base_addr);
-
 	return 0;
 }
 
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index c2227983ed88..519e4a78c8f8 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -37,6 +37,8 @@
  */
 #define TPM_POLL_SLEEP	1  /* msec */
 
+static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value);
+
 static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
 					bool check_cancel, bool *canceled)
 {
@@ -716,8 +718,7 @@ void tpm_tis_remove(struct tpm_chip *chip)
 	u32 interrupt;
 	int rc;
 
-	if (chip->ops->clk_enable != NULL)
-		chip->ops->clk_enable(chip, true);
+	tpm_tis_clkrun_enable(chip, true);
 
 	rc = tpm_tis_read32(priv, reg, &interrupt);
 	if (rc < 0)
@@ -725,8 +726,10 @@ void tpm_tis_remove(struct tpm_chip *chip)
 
 	tpm_tis_write32(priv, reg, ~TPM_GLOBAL_INT_ENABLE & interrupt);
 
-	if (chip->ops->clk_enable != NULL)
-		chip->ops->clk_enable(chip, false);
+	tpm_tis_clkrun_enable(chip, false);
+
+	if (priv->ilb_base_addr)
+		iounmap(priv->ilb_base_addr);
 }
 EXPORT_SYMBOL_GPL(tpm_tis_remove);
 
@@ -736,6 +739,9 @@ void tpm_tis_remove(struct tpm_chip *chip)
  * @chip:	TPM chip to use
  * @value:	1 - Disable CLKRUN protocol, so that clocks are free running
  *		0 - Enable CLKRUN protocol
+ *
+ * Call this function directly in tpm_tis_remove() in error or driver removal
+ * path, since the chip->ops is set to NULL in tpm_chip_unregister().
  */
 static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value)
 {
@@ -922,21 +928,20 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 	}
 
 	rc = tpm_chip_register(chip);
-	if (rc && is_bsw())
-		iounmap(priv->ilb_base_addr);
+	if (rc)
+		goto out_err;
 
 	if (chip->ops->clk_enable != NULL)
 		chip->ops->clk_enable(chip, false);
 
-	return rc;
-out_err:
-	tpm_tis_remove(chip);
-	if (is_bsw())
-		iounmap(priv->ilb_base_addr);
+	return 0;
 
-	if (chip->ops->clk_enable != NULL)
+out_err:
+	if ((chip->ops != NULL) && (chip->ops->clk_enable != NULL))
 		chip->ops->clk_enable(chip, false);
 
+	tpm_tis_remove(chip);
+
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm_tis_core_init);
-- 
1.9.1