linux-kernel - [PATCH] RTC: Prevents a division by zero in kernel code.

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Date:	Wed,  2 Feb 2011 16:04:02 -0200
From:	Marcelo Roberto Jimenez <mroberto@...i.cetuc.puc-rio.br>
To:	mroberto@...i.cetuc.puc-rio.br, a.zummo@...ertech.it,
	john.stultz@...aro.org
Cc:	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org
Subject: [PATCH] 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.

Signed-off-by: Marcelo Roberto Jimenez <mroberto@...i.cetuc.puc-rio.br>
---
 drivers/rtc/interface.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 925006d..a0c0196 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -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;
-- 
1.7.3.4

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