diff options
| author | Johan Hovold <johan@kernel.org> | 2017-06-06 17:59:03 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-07-27 15:07:55 -0700 |
| commit | 76572609e45895826f4bf49c376271dc62f125dc (patch) | |
| tree | 2704c82c55425368456b3f5982bde33fde1279c3 | |
| parent | 60813b6a2ab40c8ad7f5e44819fe6e44fa4b459a (diff) | |
thermal: max77620: fix device-node reference imbalance
commit c592fafbdbb6b1279b76a54722d1465ca77e5bde upstream.
The thermal child device reuses the parent MFD-device device-tree node
when registering a thermal zone, but did not take a reference to the
node.
This leads to a reference imbalance, and potential use-after-free, when
the node reference is dropped by the platform-bus device destructor
(once for the child and later again for the parent).
Fix this by dropping any reference already held to a device-tree node
and getting a reference to the parent's node which will be balanced on
reprobe or on platform-device release, whichever comes first.
Note that simply clearing the of_node pointer on probe errors and on
driver unbind would not allow the use of device-managed resources as
specifically thermal_zone_of_sensor_unregister() claims that a valid
device-tree node pointer is needed during deregistration (even if it
currently does not seem to use it).
Fixes: ec4664b3fd6d ("thermal: max77620: Add thermal driver for reporting junction temp")
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/thermal/max77620_thermal.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/thermal/max77620_thermal.c b/drivers/thermal/max77620_thermal.c index 83905ff46e40..7e989277a890 100644 --- a/drivers/thermal/max77620_thermal.c +++ b/drivers/thermal/max77620_thermal.c @@ -104,8 +104,6 @@ static int max77620_thermal_probe(struct platform_device *pdev) return -EINVAL; } - pdev->dev.of_node = pdev->dev.parent->of_node; - mtherm->dev = &pdev->dev; mtherm->rmap = dev_get_regmap(pdev->dev.parent, NULL); if (!mtherm->rmap) { @@ -113,6 +111,14 @@ static int max77620_thermal_probe(struct platform_device *pdev) return -ENODEV; } + /* + * Drop any current reference to a device-tree node and get a + * reference to the parent's node which will be balanced on reprobe or + * on platform-device release. + */ + of_node_put(pdev->dev.of_node); + pdev->dev.of_node = of_node_get(pdev->dev.parent->of_node); + mtherm->tz_device = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, mtherm, &max77620_thermal_ops); if (IS_ERR(mtherm->tz_device)) { |