On 18/03/2025 00:03:43+0530, Bharadwaj Raju wrote:
> The trace call invokes rtc_tm_to_time64 on a
> potentially uninitialized alarm->time. Move the
> trace call to the path where we do successfully
> initialize and read that struct.
>
> This fixes a KMSAN warning.
>
> Fixes: 29a1f599c0cc ("rtc: Add tracepoints for RTC system")
>
> Signed-off-by: Bharadwaj Raju <bharadwaj.raju777@xxxxxxxxx>
> ---
> drivers/rtc/interface.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
> index aaf76406cd7d..82ba33bf478b 100644
> --- a/drivers/rtc/interface.c
> +++ b/drivers/rtc/interface.c
> @@ -201,11 +201,12 @@ static int rtc_read_alarm_internal(struct rtc_device *rtc,
> alarm->time.tm_yday = -1;
> alarm->time.tm_isdst = -1;
> err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
> + if (!err)
> + trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
> }
>
> mutex_unlock(&rtc->ops_lock);
>
> - trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
This removes the tracepoint when there is an error, rendering it les
useful.
Also, as discussed about a year ago, alarm-time being uninitialized is
not actually an issue as mktime64 can handle whatever is the input so
this will never cause any problem so this isn't really a fix.
I suggest the following:
---
From: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Subject: [PATCH] rtc: interface: silence KMSAN warning
KMSAN complains that alarm->time can be used uninitialized. Pass 0 to
trace_rtc_read_alarm in case it has not been set.
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
---
drivers/rtc/interface.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index aaf76406cd7d..dc741ba29fa3 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -205,7 +205,7 @@ static int rtc_read_alarm_internal(struct rtc_device *rtc,
mutex_unlock(&rtc->ops_lock);
- trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
+ trace_rtc_read_alarm(err?0:rtc_tm_to_time64(&alarm->time), err);
return err;
}
--
2.48.1
²
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
