mfd: max8997: Fix possible NULL pointer dereference on i2c_new_dummy error

During probe the driver allocates dummy I2C devices for RTC, haptic and
MUIC 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, haptic or MUIC 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, 18 insertions, 0 deletions

diff --git a/drivers/mfd/max8997.c b/drivers/mfd/max8997.c
index 5adede0fb04c..8cf7a015cfe5 100644
--- a/drivers/mfd/max8997.c
+++ b/drivers/mfd/max8997.c
@@ -208,10 +208,26 @@ static int max8997_i2c_probe(struct i2c_client *i2c,
         mutex_init(&max8997->iolock);
 
         max8997->rtc = i2c_new_dummy(i2c->adapter, I2C_ADDR_RTC);
+        if (!max8997->rtc) {
+                dev_err(max8997->dev, "Failed to allocate I2C device for RTC\n");
+                return -ENODEV;
+        }
         i2c_set_clientdata(max8997->rtc, max8997);
+
         max8997->haptic = i2c_new_dummy(i2c->adapter, I2C_ADDR_HAPTIC);
+        if (!max8997->haptic) {
+                dev_err(max8997->dev, "Failed to allocate I2C device for Haptic\n");
+                ret = -ENODEV;
+                goto err_i2c_haptic;
+        }
         i2c_set_clientdata(max8997->haptic, max8997);
+
         max8997->muic = i2c_new_dummy(i2c->adapter, I2C_ADDR_MUIC);
+        if (!max8997->muic) {
+                dev_err(max8997->dev, "Failed to allocate I2C device for MUIC\n");
+                ret = -ENODEV;
+                goto err_i2c_muic;
+        }
         i2c_set_clientdata(max8997->muic, max8997);
 
         pm_runtime_set_active(max8997->dev);
@@ -239,7 +255,9 @@ static int max8997_i2c_probe(struct i2c_client *i2c,
 err_mfd:
         mfd_remove_devices(max8997->dev);
         i2c_unregister_device(max8997->muic);
+err_i2c_muic:
         i2c_unregister_device(max8997->haptic);
+err_i2c_haptic:
         i2c_unregister_device(max8997->rtc);
         return ret;
 }