[PATCH] tpm: check the chip reference before using it

[Andi Shyti <andi.shyti@gmail.com>]

If a driver calls tpm_dev_vendor_release for a device already released
then the driver will oops.

Signed-off-by: Andi Shyti <andi.shyti@gmail.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
---
 drivers/char/tpm/tpm.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index ad7c732..66e4c12 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1322,6 +1322,9 @@ EXPORT_SYMBOL_GPL(tpm_pm_resume);
 
 void tpm_dev_vendor_release(struct tpm_chip *chip)
 {
+	if (!chip)
+		return;
+
 	if (chip->vendor.release)
 		chip->vendor.release(chip->dev);
 
@@ -1337,6 +1340,9 @@ EXPORT_SYMBOL_GPL(tpm_dev_vendor_release);
  */
 void tpm_dev_release(struct device *dev)
 {
+	if (!chip)
+		return;
+
 	struct tpm_chip *chip = dev_get_drvdata(dev);
 
 	tpm_dev_vendor_release(chip);
-- 
1.7.10