[PATCH 3.13 069/151] mfd: max77686: Fix possible NULL pointer dereference on i2c_new_dummy error

Kamal Mostafa kamal at canonical.com
Fri May 2 15:37:37 UTC 2014 -stable review patch.  If anyone has any objections, please let me know.


From: Krzysztof Kozlowski <k.kozlowski at samsung.com>

commit b9e183a1d495cd65412abe0f9df19b151716bfe7 upstream.

During probe the driver allocates dummy I2C device for RTC 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 used
by 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 at samsung.com>
Signed-off-by: Lee Jones <lee.jones at linaro.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/mfd/max77686.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/mfd/max77686.c b/drivers/mfd/max77686.c
index 12b3ae3..9ef7e3d 100644
--- a/drivers/mfd/max77686.c
+++ b/drivers/mfd/max77686.c
@@ -121,6 +121,10 @@ static int max77686_i2c_probe(struct i2c_client *i2c,
 		dev_info(max77686->dev, "device found\n");
 	max77686->rtc = i2c_new_dummy(i2c->adapter, I2C_ADDR_RTC);
+	if (!max77686->rtc) {
+		dev_err(max77686->dev, "Failed to allocate I2C device for RTC\n");
+		return -ENODEV;
+	}
 	i2c_set_clientdata(max77686->rtc, max77686);

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