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RTC: Prevents a division by zero in kernel code.

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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>
This commit is contained in:
Marcelo Roberto Jimenez 2011-02-02 16:04:02 -02:00 committed by John Stultz
parent 9118626a30
commit 83a06bf50b
2 changed files with 4 additions and 0 deletions
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1
drivers/rtc/class.c
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@ -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;

3
drivers/rtc/interface.c
View file

@ -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;