[PATCH resend] thermal: bcm2835: Fix crash in bcm2835_thermal_debugfs

[PATCH resend] thermal: bcm2835: Fix crash in bcm2835_thermal_debugfs

[Phil Elwell]

"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

Re: [PATCH resend] thermal: bcm2835: Fix crash in bcm2835_thermal_debugfs

[Eric Anholt]

[-- Attachment #1: Type: text/plain, Size: 779 bytes --]

Phil Elwell <phil@raspberrypi.org> writes:

> "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>

Acked-by: Eric Anholt <eric@anholt.net>

From the thread that missed Ccing the maintainers there was also:

Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]