2017-12-13 13:53:35

by Jia-Ju Bai

Subject: [PATCH 1/2] rtc-r7301: Fix a possible sleep-in-atomic bug in rtc7301_read_time

The driver may sleep under a spinlock.
The function call path is:
rtc7301_read_time (acquire the spinlock)
rtc7301_wait_while_busy
usleep_range --> may sleep

To fix it, usleep_range is replaced with udelay.

This bug is found by my static analysis tool(DSAC) and checked by my code review.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/rtc/rtc-r7301.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-r7301.c b/drivers/rtc/rtc-r7301.c
index 28d5408..d846e97 100644
--- a/drivers/rtc/rtc-r7301.c
+++ b/drivers/rtc/rtc-r7301.c
@@ -95,7 +95,7 @@ static int rtc7301_wait_while_busy(struct rtc7301_priv *priv)
if (!(val & RTC7301_CONTROL_BUSY))
return 0;

- usleep_range(200, 300);
+ udelay(300);
}

return -ETIMEDOUT;
--
1.7.9.5

2017-12-18 22:24:51

by Alexandre Belloni

Subject: Re: [PATCH 1/2] rtc-r7301: Fix a possible sleep-in-atomic bug in rtc7301_read_time

On 13/12/2017 at 21:55:50 +0800, Jia-Ju Bai wrote:
> The driver may sleep under a spinlock.
> The function call path is:
> rtc7301_read_time (acquire the spinlock)
> rtc7301_wait_while_busy
> usleep_range --> may sleep
>
> To fix it, usleep_range is replaced with udelay.
>
> This bug is found by my static analysis tool(DSAC) and checked by my code review.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> drivers/rtc/rtc-r7301.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
Applied, thanks.

--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com