The current code passes the address of tpm_chip as the argument to
dev_get_drvdata() without prior NULL check in
tpm_ibmvtpm_get_desired_dma. This resulted an oops during kernel
boot when vTPM is enabled in Power partition configured in active
memory sharing mode.
The vio_driver's get_desired_dma() is called before the probe(), which
for vtpm is tpm_ibmvtpm_probe, and it's this latter function that
initializes the driver and set data. Attempting to get data before
the probe() caused the problem.
This patch adds a NULL check to the tpm_ibmvtpm_get_desired_dma.
fixes: 9e0d39d8a6a0 ("tpm: Remove useless priv field in struct tpm_vendor_specific")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Hon Ching(Vicky) Lo <honclo@xxxxxxxxxxxxxxxxxx>
---
drivers/char/tpm/tpm_ibmvtpm.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index 1b9d61f..a88ee25 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -313,7 +313,10 @@ static int tpm_ibmvtpm_remove(struct vio_dev *vdev)
static unsigned long tpm_ibmvtpm_get_desired_dma(struct vio_dev *vdev)
{
struct tpm_chip *chip = dev_get_drvdata(&vdev->dev);
- struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
+ struct ibmvtpm_dev *ibmvtpm = NULL;
+
+ if (chip)
+ ibmvtpm = dev_get_drvdata(&chip->dev);
/*
* ibmvtpm initializes at probe time, so the data we are
--
1.7.1