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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Phil Elwell <phil@raspberrypi.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 13/92] thermal: bcm2835: Fix crash in bcm2835_thermal_debugfs
Date:   Thu, 18 Apr 2019 19:56:31 +0200
Message-Id: <20190418160431.531864834@linuxfoundation.org>
In-Reply-To: <20190418160430.325165109@linuxfoundation.org>
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[ Upstream commit 35122495a8c6683e863acf7b05a7036b2be64c7a ]

"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>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.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 24b006a95142..8646fb7425f2 100644
--- a/drivers/thermal/broadcom/bcm2835_thermal.c
+++ b/drivers/thermal/broadcom/bcm2835_thermal.c
@@ -128,8 +128,7 @@ 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);
@@ -275,7 +274,7 @@ 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,
@@ -299,8 +298,8 @@ 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);
-- 
2.19.1