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vTPM: Fix missing NULL check

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commit 31574d321c70f6d3b40fe98f9b2eafd9a903fef9 upstream.

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: 9e0d39d8a6 ("tpm: Remove useless priv field in struct tpm_vendor_specific")
Signed-off-by: Hon Ching(Vicky) Lo <honclo@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkine <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hon Ching \(Vicky) Lo 2017-03-15 01:28:07 -04:00 • committed by Greg Kroah-Hartman
commit 7dfe7ca9ec
1 changed files with 11 additions and 6 deletions
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17
drivers/char/tpm/tpm_ibmvtpm.c
View file

@ -295,6 +295,8 @@ static int tpm_ibmvtpm_remove(struct vio_dev *vdev)
}
kfree(ibmvtpm);
/* For tpm_ibmvtpm_get_desired_dma */
dev_set_drvdata(&vdev->dev, NULL);
return 0;
}
@ -309,13 +311,16 @@ 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;
/* ibmvtpm initializes at probe time, so the data we are
* asking for may not be set yet. Estimate that 4K required
* for TCE-mapped buffer in addition to CRQ.
*/
if (!ibmvtpm)
/*
* ibmvtpm initializes at probe time, so the data we are
* asking for may not be set yet. Estimate that 4K required
* for TCE-mapped buffer in addition to CRQ.
*/
if (chip)
ibmvtpm = dev_get_drvdata(&chip->dev);
else
return CRQ_RES_BUF_SIZE + PAGE_SIZE;
return CRQ_RES_BUF_SIZE + ibmvtpm->rtce_size;