linux-kernel - [PATCH 3.11 072/182] mfd: max8925: Fix possible NULL pointer dereference on i2c_new

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Message-Id: <1398329507-5911-73-git-send-email-luis.henriques@canonical.com>
Date:	Thu, 24 Apr 2014 09:49:57 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Lee Jones <lee.jones@...aro.org>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.11 072/182] mfd: max8925: Fix possible NULL pointer dereference on i2c_new_dummy error

3.11.10.9 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Krzysztof Kozlowski <k.kozlowski@...sung.com>

commit 96cf3dedc491d2f1f66cc26217f2b06b0c7b6797 upstream.

During probe the driver allocates dummy I2C devices for RTC and ADC
with i2c_new_dummy() but it does not check the return value of this
calls.

In case of error (i2c_new_device(): memory allocation failure or I2C
address cannot be used) this function returns NULL which is later used
by i2c_unregister_device().

If i2c_new_dummy() fails for RTC or ADC devices, fail also the probe
for main MFD driver.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/mfd/max8925-i2c.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/mfd/max8925-i2c.c b/drivers/mfd/max8925-i2c.c
index 8042b32..edc9eac 100644
--- a/drivers/mfd/max8925-i2c.c
+++ b/drivers/mfd/max8925-i2c.c
@@ -181,9 +181,18 @@ static int max8925_probe(struct i2c_client *client,
 	mutex_init(&chip->io_lock);
 
 	chip->rtc = i2c_new_dummy(chip->i2c->adapter, RTC_I2C_ADDR);
+	if (!chip->rtc) {
+		dev_err(chip->dev, "Failed to allocate I2C device for RTC\n");
+		return -ENODEV;
+	}
 	i2c_set_clientdata(chip->rtc, chip);
 
 	chip->adc = i2c_new_dummy(chip->i2c->adapter, ADC_I2C_ADDR);
+	if (!chip->adc) {
+		dev_err(chip->dev, "Failed to allocate I2C device for ADC\n");
+		i2c_unregister_device(chip->rtc);
+		return -ENODEV;
+	}
 	i2c_set_clientdata(chip->adc, chip);
 
 	device_init_wakeup(&client->dev, 1);
-- 
1.9.1

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