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Commit a015dbc1 authored by John Stultz's avatar John Stultz
Browse files

rtc: m41t80: Initialize clientdata before registering device 



Commit f44f7f96 ("RTC: Initialize kernel state from RTC") uncovered
an issue in a number of RTC drivers, where the drivers call
rtc_device_register before initializing the clientdata.

This frequently results in null pointer dereferences when the
rtc_device_register immediately makes use of the rtc device, calling
rtc_read_alarm.

The solution is to ensure the clientdata is initialized prior to registering
the rtc device.

CC: Wolfram Sang <w.sang@pengutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: rtc-linux@googlegroups.com
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 9a281a67

drivers/rtc/rtc-m41t80.c

+3 −2
Original line number Original line Diff line number Diff line
@@ -783,6 +783,9 @@ static int m41t80_probe(struct i2c_client *client, 
		goto exit;

		goto exit;

	}

	}





	clientdata->features = id->driver_data;

	i2c_set_clientdata(client, clientdata);



	rtc = rtc_device_register(client->name, &client->dev,

	rtc = rtc_device_register(client->name, &client->dev,

				  &m41t80_rtc_ops, THIS_MODULE);

				  &m41t80_rtc_ops, THIS_MODULE);

	if (IS_ERR(rtc)) {

	if (IS_ERR(rtc)) {
@@ -792,8 +795,6 @@ static int m41t80_probe(struct i2c_client *client, 
	}

	}





	clientdata->rtc = rtc;

	clientdata->rtc = rtc;

	clientdata->features = id->driver_data;

	i2c_set_clientdata(client, clientdata);





	/* Make sure HT (Halt Update) bit is cleared */

	/* Make sure HT (Halt Update) bit is cleared */

	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);

	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);