Patchwork [05/11] rtc: m41t80: Initialize clientdata before registering device

login
register
mail settings
Submitter John Stultz
Date May 7, 2011, 1:20 a.m.
Message ID <1304731254-3238-6-git-send-email-john.stultz@linaro.org>
Download mbox | patch
Permalink /patch/94452/
State New
Headers show

Comments

John Stultz - May 7, 2011, 1:20 a.m.
Commit f44f7f96a20 ("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: John Stultz <john.stultz@linaro.org>
---
 drivers/rtc/rtc-m41t80.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index 69fe664..eda128f 100644
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -783,6 +783,9 @@  static int m41t80_probe(struct i2c_client *client,
 		goto exit;
 	}
 
+	clientdata->features = id->driver_data;
+	i2c_set_clientdata(client, clientdata);
+
 	rtc = rtc_device_register(client->name, &client->dev,
 				  &m41t80_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc)) {
@@ -792,8 +795,6 @@  static int m41t80_probe(struct i2c_client *client,
 	}
 
 	clientdata->rtc = rtc;
-	clientdata->features = id->driver_data;
-	i2c_set_clientdata(client, clientdata);
 
 	/* Make sure HT (Halt Update) bit is cleared */
 	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);