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authorJohan Hovold <johan@kernel.org>2017-06-06 17:59:03 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-13 11:07:32 +0200
commitc592fafbdbb6b1279b76a54722d1465ca77e5bde (patch)
treee4b16473544b1449cc74caae9671889495af0cf5 /drivers/thermal
parent2bf698671205bb6f898db348b788d16f6976e086 (diff)
downloadlinux-c592fafbdbb6b1279b76a54722d1465ca77e5bde.tar.bz2
thermal: max77620: fix device-node reference imbalance
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: stable <stable@vger.kernel.org> # 4.9 Cc: Laxman Dewangan <ldewangan@nvidia.com> Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/thermal')
-rw-r--r--drivers/thermal/max77620_thermal.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/thermal/max77620_thermal.c b/drivers/thermal/max77620_thermal.c
index e9a1fe342760..71d35f3c9215 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)) {