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Subject[PATCH 1/2] tpm/tpm_ibmvtpm: Fail in ibmvtpm_get_data if driver_data is bad
I'm looking at an oops in tpm_ibmvtpm_get_desired_dma:

28: 00 00 20 39 li r9,0
2c: 10 00 01 e8 ld r0,16(r1)
30: 28 00 69 80 lwz r3,40(r9)

We set r9 to 0 then load r9+40. The problem is actually in
ibmvtpm_get_data, it can return NULL but the rest of the driver
never expects it.

Add a BUG_ON in ibmvtpm_get_data. We still need to identify the root
cause but at least this makes it obvious what went wrong.

Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard <anton@samba.org>
---

diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index af74c57..0d1eeba 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -63,9 +63,9 @@ static int ibmvtpm_send_crq(struct vio_dev *vdev, u64 w1, u64 w2)
static struct ibmvtpm_dev *ibmvtpm_get_data(const struct device *dev)
{
struct tpm_chip *chip = dev_get_drvdata(dev);
- if (chip)
- return (struct ibmvtpm_dev *)TPM_VPRIV(chip);
- return NULL;
+
+ BUG_ON(!chip);
+ return (struct ibmvtpm_dev *)TPM_VPRIV(chip);
}

/**

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