Commit 83a06bf5 authored Feb 02, 2011 by Marcelo Roberto Jimenez Committed by John Stultz Feb 03, 2011

RTC: Prevents a division by zero in kernel code.



This patch prevents a user space program from calling the RTC_IRQP_SET
ioctl with a negative value of frequency. Also, if this call is make
with a zero value of frequency, there would be a division by zero in the
kernel code.

[jstultz: Also initialize irq_freq to 1 to catch other divbyzero issues]

CC: Alessandro Zummo <a.zummo@towertech.it>
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marcelo Roberto Jimenez <mroberto@cpti.cetuc.puc-rio.br>
Signed-off-by: John Stultz <john.stultz@linaro.org>

parent 9118626a

drivers/rtc/class.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -143,6 +143,7 @@ struct rtc_device rtc_device_register(const char name, struct device *dev,
		rtc->id = id;
		rtc->ops = ops;
		rtc->owner = owner;
		rtc->irq_freq = 1;
		rtc->max_user_freq = 64;
		rtc->dev.parent = dev;
		rtc->dev.class = rtc_class;

drivers/rtc/interface.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -464,6 +464,9 @@ int rtc_irq_set_freq(struct rtc_device rtc, struct rtc_task task, int freq)
		int err = 0;
		unsigned long flags;

		if (freq <= 0)
		return -EINVAL;

		spin_lock_irqsave(&rtc->irq_task_lock, flags);
		if (rtc->irq_task != NULL && task == NULL)
		err = -EBUSY;