linux-kernel - [RFT PATCH 2/4] compal-laptop: Check return value of power_supply

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Date:	Tue, 27 Jan 2015 12:30:19 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Dmitry Artamonow <mad_soft@...ox.ru>,
	Marek Belisko <marek@...delico.com>,
	Cezary Jackiewicz <cezary.jackiewicz@...il.com>,
	Darren Hart <dvhart@...radead.org>,
	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org
Cc:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	stable@...r.kernel.org
Subject: [RFT PATCH 2/4] compal-laptop: Check return value of
 power_supply_register

The return value of power_supply_register() call was not checked and
even on error probe() function returned 0. If registering failed then
during unbind the driver tried to unregister power supply which was not
actually registered.

This could lead to memory corruption because power_supply_unregister()
unconditionally cleans up given power supply.

Fix this by checking return status of power_supply_register() call. In
case of failure, unregister the hwmon device and fail the probe. Add a
fixme note about missing hwmon_device_unregister() in driver removal.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
Fixes: 9be0fcb5ed46 ("compal-laptop: add JHL90, battery & hwmon interface")
Cc: <stable@...r.kernel.org>
---
 drivers/platform/x86/compal-laptop.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/compal-laptop.c b/drivers/platform/x86/compal-laptop.c
index 15c0fab2bfa1..cf55a9246f12 100644
--- a/drivers/platform/x86/compal-laptop.c
+++ b/drivers/platform/x86/compal-laptop.c
@@ -1036,12 +1036,16 @@ static int compal_probe(struct platform_device *pdev)
 
 	/* Power supply */
 	initialize_power_supply_data(data);
-	power_supply_register(&compal_device->dev, &data->psy);
+	err = power_supply_register(&compal_device->dev, &data->psy);
+	if (err < 0)
+		goto psy_err;
 
 	platform_set_drvdata(pdev, data);
 
 	return 0;
 
+psy_err:
+	hwmon_device_unregister(hwmon_dev);
 remove:
 	sysfs_remove_group(&pdev->dev.kobj, &compal_platform_attr_group);
 	return err;
@@ -1072,6 +1076,7 @@ static int compal_remove(struct platform_device *pdev)
 
 	data = platform_get_drvdata(pdev);
 	power_supply_unregister(&data->psy);
+	/* FIXME: missing hwmon_device_unregister() */
 
 	sysfs_remove_group(&pdev->dev.kobj, &compal_platform_attr_group);
 
-- 
1.9.1

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