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

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Krzysztof Kozlowski

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Mar 6, 2014, 4:40:01 AM3/6/14
to
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.koz...@samsung.com>
---
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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Beomho Seo

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Mar 6, 2014, 7:40:02 PM3/6/14
to
On 03/06/2014 06:33 PM, Krzysztof Kozlowski wrote:
> 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.koz...@samsung.com>

Thanks,

Acked-by: Beomho Seo <beomh...@samsung.com>
Best Regards,

Jonathan Cameron

unread,
Mar 15, 2014, 12:30:01 PM3/15/14
to
On 06/03/14 09:33, Krzysztof Kozlowski wrote:
> 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.koz...@samsung.com>
Good catch, but the error path needs more care.
> ---
> 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;
> + }
The two failures need to be handled independently as we only want to unregister
those that succeeded. i2c_new_dummy will not return an error and leave a device
registered. This is particularly true given the first thing that i2c_unregister_device
does is to derefence the client pointer. That will cause a segfault if you do it
for NULL as here.

> 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);
Good catch.
>
> return 0;

Krzysztof Kozlowski

unread,
Mar 17, 2014, 4:10:01 AM3/17/14
to
Hi,
Where the segfault would occur? If i2c_new_dummy fails then
i2c_unregister_device() will be called only on NON-null values:
+error_i2c_unregister:
+ if (cm36651->ps_client)
+ i2c_unregister_device(cm36651->ps_client);
+ if (cm36651->ara_client)
+ i2c_unregister_device(cm36651->ara_client);

If probe() succeeds (both i2c_new_dummy return proper pointer) then
remove() will unregister two i2c devices.

Jonathan Cameron

unread,
Mar 17, 2014, 3:30:02 PM3/17/14
to
Oops, I missed that. Still, the form of this is unusual so please
change it to the more conventional option of a goto per error rather
than grouping them. That will also allow you to drop the null checks
below leading to a more obviously correct error path.
>
>>> 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);
>> Good catch.
>>>
>>> return 0;
>>> }
>>>
>
> --
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Krzysztof Kozlowski

unread,
Mar 18, 2014, 4:10:01 AM3/18/14
to
Sure, I'll send a fixed version.

Best regards,
Krzysztof

Krzysztof Kozlowski

unread,
Mar 18, 2014, 4:20:02 AM3/18/14
to
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.koz...@samsung.com>
Acked-by: Beomho Seo <beomh...@samsung.com>
---
drivers/iio/light/cm36651.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/light/cm36651.c b/drivers/iio/light/cm36651.c
index a45e07492db3..39fc67e82138 100644
--- a/drivers/iio/light/cm36651.c
+++ b/drivers/iio/light/cm36651.c
@@ -652,7 +652,19 @@ static int cm36651_probe(struct i2c_client *client,
cm36651->client = client;
cm36651->ps_client = i2c_new_dummy(client->adapter,
CM36651_I2C_ADDR_PS);
+ if (!cm36651->ps_client) {
+ dev_err(&client->dev, "%s: new i2c device failed\n", __func__);
+ ret = -ENODEV;
+ goto error_disable_reg;
+ }
+
cm36651->ara_client = i2c_new_dummy(client->adapter, CM36651_ARA);
+ if (!cm36651->ara_client) {
+ dev_err(&client->dev, "%s: new i2c device failed\n", __func__);
+ ret = -ENODEV;
+ goto error_i2c_unregister_ps;
+ }
+
mutex_init(&cm36651->lock);
indio_dev->dev.parent = &client->dev;
indio_dev->channels = cm36651_channels;
@@ -664,7 +676,7 @@ static int cm36651_probe(struct i2c_client *client,
ret = cm36651_setup_reg(cm36651);
if (ret) {
dev_err(&client->dev, "%s: register setup failed\n", __func__);
- goto error_disable_reg;
+ goto error_i2c_unregister_ara;
}

ret = request_threaded_irq(client->irq, NULL, cm36651_irq_handler,
@@ -672,7 +684,7 @@ static int cm36651_probe(struct i2c_client *client,
"cm36651", indio_dev);
if (ret) {
dev_err(&client->dev, "%s: request irq failed\n", __func__);
- goto error_disable_reg;
+ goto error_i2c_unregister_ara;
}

ret = iio_device_register(indio_dev);
@@ -685,6 +697,10 @@ static int cm36651_probe(struct i2c_client *client,

error_free_irq:
free_irq(client->irq, indio_dev);
+error_i2c_unregister_ara:
+ i2c_unregister_device(cm36651->ara_client);
+error_i2c_unregister_ps:
+ i2c_unregister_device(cm36651->ps_client);
error_disable_reg:
regulator_disable(cm36651->vled_reg);
return ret;
@@ -698,6 +714,8 @@ 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

Jonathan Cameron

unread,
Mar 22, 2014, 8:30:03 AM3/22/14
to
On 18/03/14 08:13, Krzysztof Kozlowski wrote:
> 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.koz...@samsung.com>
> Acked-by: Beomho Seo <beomh...@samsung.com>
Applied to the fixes-togreg branch of iio.git and marked for
stable.

This will probably go in shortly after the 3.15-rc1
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