mfd: max8925: Fix possible NULL pointer dereference on i2c_new_dummy error

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.

Cc: stable@vger.kernel.org
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/mfd/max8925-i2c.c b/drivers/mfd/max8925-i2c.c
index 176aa26fc787..a83eed5c15ca 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);