[3.13.y.z extended stable] Patch "mfd: max77686: Fix possible NULL pointer dereference on i2c_new_dummy error" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Thu May 1 19:17:19 UTC 2014

This is a note to let you know that I have just added a patch titled

    mfd: max77686: Fix possible NULL pointer dereference on i2c_new_dummy error

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see



>From 392ebd8728b7aea6a514358435bcbe870732aa79 Mon Sep 17 00:00:00 2001
From: Krzysztof Kozlowski <k.kozlowski at samsung.com>
Date: Tue, 11 Feb 2014 11:03:31 +0100
Subject: mfd: max77686: Fix possible NULL pointer dereference on i2c_new_dummy

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);


More information about the kernel-team mailing list