mfd: sec-core: Fix possible NULL pointer dereference when i2c_new_dummy error

commit 65aba1e0 upstream.

During probe the sec-core driver allocates dummy I2C device for RTC with
i2c_new_dummy() but return value is not checked. 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
devm_regmap_init_i2c() or i2c_unregister_device().

If i2c_new_dummy() fails for RTC device, fail also the probe for main
MFD driver.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

drivers/mfd/sec-core.c

@@ -274,6 +274,10 @@ static int sec_pmic_probe(struct i2c_client *i2c,
 	}
 
 	sec_pmic->rtc = i2c_new_dummy(i2c->adapter, RTC_I2C_ADDR);
+	if (!sec_pmic->rtc) {
+		dev_err(&i2c->dev, "Failed to allocate I2C for RTC\n");
+		return -ENODEV;
+	}
 	i2c_set_clientdata(sec_pmic->rtc, sec_pmic);
 
 	if (pdata && pdata->cfg_pmic_irq)