linux-kernel - [PATCH 09/11] rtc: pcap: Initialize drvdata before registering device

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Message-Id: <1304731254-3238-10-git-send-email-john.stultz@linaro.org>
Date:	Fri,  6 May 2011 18:20:52 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	John Stultz <john.stultz@...aro.org>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Thomas Gleixner <tglx@...utronix.de>,
	rtc-linux@...glegroups.com
Subject: [PATCH 09/11] rtc: pcap: Initialize drvdata before registering device

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 device or platform drvdata.

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 drvdata is initialized prior to registering
the rtc device.

CC: Wolfram Sang <w.sang@...gutronix.de>
CC: Alessandro Zummo <a.zummo@...ertech.it>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: rtc-linux@...glegroups.com
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 drivers/rtc/rtc-pcap.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/rtc/rtc-pcap.c b/drivers/rtc/rtc-pcap.c
index a633abc..cd4f198 100644
--- a/drivers/rtc/rtc-pcap.c
+++ b/drivers/rtc/rtc-pcap.c
@@ -151,6 +151,8 @@ static int __devinit pcap_rtc_probe(struct platform_device *pdev)
 
 	pcap_rtc->pcap = dev_get_drvdata(pdev->dev.parent);
 
+	platform_set_drvdata(pdev, pcap_rtc);
+
 	pcap_rtc->rtc = rtc_device_register("pcap", &pdev->dev,
 				  &pcap_rtc_ops, THIS_MODULE);
 	if (IS_ERR(pcap_rtc->rtc)) {
@@ -158,7 +160,6 @@ static int __devinit pcap_rtc_probe(struct platform_device *pdev)
 		goto fail_rtc;
 	}
 
-	platform_set_drvdata(pdev, pcap_rtc);
 
 	timer_irq = pcap_to_irq(pcap_rtc->pcap, PCAP_IRQ_1HZ);
 	alarm_irq = pcap_to_irq(pcap_rtc->pcap, PCAP_IRQ_TODA);
@@ -177,6 +178,7 @@ fail_alarm:
 fail_timer:
 	rtc_device_unregister(pcap_rtc->rtc);
 fail_rtc:
+	platform_set_drvdata(pdev, NULL);
 	kfree(pcap_rtc);
 	return err;
 }
-- 
1.7.3.2.146.gca209

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