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Subject[PATCH] thermal: bcm2835: Fix crash in bcm2835_thermal_debugfs
Date
"cat /sys/kernel/debug/bcm2835_thermal/regset" causes a NULL pointer
dereference in bcm2835_thermal_debugfs. The driver makes use of the
implementation details of the thermal framework to retrieve a pointer
to its private data from a struct thermal_zone_device, and gets it
wrong - leading to the crash. Instead, store its private data as the
drvdata and retrieve the thermal_zone_device pointer from it.

Fixes: bcb7dd9ef206 ("thermal: bcm2835: add thermal driver for bcm2835 SoC")

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
drivers/thermal/broadcom/bcm2835_thermal.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/thermal/broadcom/bcm2835_thermal.c b/drivers/thermal/broadcom/bcm2835_thermal.c
index 720760c..ba39647 100644
--- a/drivers/thermal/broadcom/bcm2835_thermal.c
+++ b/drivers/thermal/broadcom/bcm2835_thermal.c
@@ -119,8 +119,7 @@ static const struct debugfs_reg32 bcm2835_thermal_regs[] = {

static void bcm2835_thermal_debugfs(struct platform_device *pdev)
{
- struct thermal_zone_device *tz = platform_get_drvdata(pdev);
- struct bcm2835_thermal_data *data = tz->devdata;
+ struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
struct debugfs_regset32 *regset;

data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
@@ -266,7 +265,7 @@ static int bcm2835_thermal_probe(struct platform_device *pdev)

data->tz = tz;

- platform_set_drvdata(pdev, tz);
+ platform_set_drvdata(pdev, data);

/*
* Thermal_zone doesn't enable hwmon as default,
@@ -290,8 +289,8 @@ static int bcm2835_thermal_probe(struct platform_device *pdev)

static int bcm2835_thermal_remove(struct platform_device *pdev)
{
- struct thermal_zone_device *tz = platform_get_drvdata(pdev);
- struct bcm2835_thermal_data *data = tz->devdata;
+ struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
+ struct thermal_zone_device *tz = data->tz;

debugfs_remove_recursive(data->debugfsdir);
thermal_zone_of_sensor_unregister(&pdev->dev, tz);
--
2.7.4
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