linux-kernel - [RFT PATCH v2 2/2] compal-laptop: Check return value of power_supply

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Message-id: <1424437480-22364-2-git-send-email-k.kozlowski@samsung.com>
Date:	Fri, 20 Feb 2015 14:04:40 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Cezary Jackiewicz <cezary.jackiewicz@...il.com>,
	Darren Hart <dvhart@...radead.org>,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Guenter Roeck <linux@...ck-us.net>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	stable@...r.kernel.org
Subject: [RFT PATCH v2 2/2] 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, clean up sysfs entries and fail the probe.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
Fixes: 9be0fcb5ed46 ("compal-laptop: add JHL90, battery & hwmon interface")
Cc: <stable@...r.kernel.org>

---
Changes since v1:
1. Don't unregister hwmon device because previous patch solves this by
   using devm-like function.
---
 drivers/platform/x86/compal-laptop.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/compal-laptop.c b/drivers/platform/x86/compal-laptop.c
index eb9885e7fb0e..8455d50a5639 100644
--- a/drivers/platform/x86/compal-laptop.c
+++ b/drivers/platform/x86/compal-laptop.c
@@ -1036,7 +1036,9 @@ 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 remove;
 
 	platform_set_drvdata(pdev, data);
 
@@ -1072,6 +1074,7 @@ 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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