[PATCH] iio: cm36651: Fix i2c client leak and possible NULL pointer dereference

[Krzysztof Kozlowski]

During probe the driver allocates dummy I2C devices (i2c_new_dummy())
but they aren't unregistered during driver remove or probe failure.

Additionally driver does not check the return value of i2c_new_dummy().
In case of error (i2c_new_device(): memory allocation failure or I2C
address cannot be used) this function returns NULL which is later
dereferenced by i2c_smbus_{read,write}_data() functions.

Fix issues by properly checking for i2c_new_dummy() return value and
unregistering I2C devices on driver remove or probe failure.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
---
 drivers/iio/light/cm36651.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/iio/light/cm36651.c b/drivers/iio/light/cm36651.c
index a45e07492db3..e7e9a597159f 100644
--- a/drivers/iio/light/cm36651.c
+++ b/drivers/iio/light/cm36651.c
@@ -653,6 +653,11 @@ static int cm36651_probe(struct i2c_client *client,
 	cm36651->ps_client = i2c_new_dummy(client->adapter,
 						     CM36651_I2C_ADDR_PS);
 	cm36651->ara_client = i2c_new_dummy(client->adapter, CM36651_ARA);
+	if (!cm36651->ps_client || !cm36651->ara_client) {
+		dev_err(&client->dev, "%s: new i2c device failed\n", __func__);
+		ret = -ENODEV;
+		goto error_i2c_unregister;
+	}
 	mutex_init(&cm36651->lock);
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->channels = cm36651_channels;
@@ -687,6 +692,11 @@ error_free_irq:
 	free_irq(client->irq, indio_dev);
 error_disable_reg:
 	regulator_disable(cm36651->vled_reg);
+error_i2c_unregister:
+	if (cm36651->ps_client)
+		i2c_unregister_device(cm36651->ps_client);
+	if (cm36651->ara_client)
+		i2c_unregister_device(cm36651->ara_client);
 	return ret;
 }
 
@@ -698,6 +708,8 @@ static int cm36651_remove(struct i2c_client *client)
 	iio_device_unregister(indio_dev);
 	regulator_disable(cm36651->vled_reg);
 	free_irq(client->irq, indio_dev);
+	i2c_unregister_device(cm36651->ps_client);
+	i2c_unregister_device(cm36651->ara_client);
 
 	return 0;
 }
-- 
1.7.9.5

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