gpio: max732x: Fix possible NULL pointer dereference on i2c_new_dummy error

In max732x_probe() driver allocates dummy I2C device (if number of ports
is greater than 8) with i2c_new_dummy() but it does not check the return
value of this call.

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_byte() (called from max732x_readb()).

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-max732x.c b/drivers/gpio/gpio-max732x.c
index 74432daaf656..7c36f2b0983d 100644
--- a/drivers/gpio/gpio-max732x.c
+++ b/drivers/gpio/gpio-max732x.c
@@ -622,6 +622,13 @@ static int max732x_probe(struct i2c_client *client,
                 goto out_failed;
         }
 
+        if (nr_port > 8 && !chip->client_dummy) {
+                dev_err(&client->dev,
+                        "Failed to allocate second group I2C device\n");
+                ret = -ENODEV;
+                goto out_failed;
+        }
+
         mutex_init(&chip->lock);
 
         max732x_readb(chip, is_group_a(chip, 0), &chip->reg_out[0]);