Commit 31574d32 authored Mar 15, 2017 by $Hon Ching $Vicky$ Lo's avatar$ Hon Ching $Vicky$ Lo Committed by Jarkko Sakkinen Apr 03, 2017

vTPM: Fix missing NULL check



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: 9e0d39d8 ("tpm: Remove useless priv field in struct tpm_vendor_specific")
Cc: <stable@vger.kernel.org>
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>

parent 8569defd

drivers/char/tpm/tpm_ibmvtpm.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -299,6 +299,8 @@ 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;
		}
		@@ -313,14 +315,16 @@ 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)
		if (chip)
		ibmvtpm = dev_get_drvdata(&chip->dev);
		else
		return CRQ_RES_BUF_SIZE + PAGE_SIZE;

		return CRQ_RES_BUF_SIZE + ibmvtpm->rtce_size;