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From: "Hon Ching(Vicky) Lo" <>
Cc: "Hon Ching(Vicky) Lo"
	Ashley Lai <>,,,
	Peter Huewe <>
Subject: [PATCH v2] vTPM: Fix missing NULL check
Date: Wed, 15 Mar 2017 01:28:07 -0400	[thread overview]
Message-ID: <> (raw)

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: <>
Signed-off-by: Hon Ching(Vicky) Lo <>
 drivers/char/tpm/tpm_ibmvtpm.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index 1b9d61f..f01d083 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -299,6 +299,8 @@ static int tpm_ibmvtpm_remove(struct vio_dev *vdev)
+	/* 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 + ibmvtpm->rtce_size;

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             reply	other threads:[~2017-03-15  5:28 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-15  5:28 Hon Ching(Vicky) Lo [this message]
     [not found] ` <>
2017-03-15 16:43   ` [PATCH v2] vTPM: Fix missing NULL check Jarkko Sakkinen

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