This is a note to let you know that I've just added the patch titled
rtc: mc146818-lib: fix locking in mc146818_set_time
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rtc-mc146818-lib-fix-locking-in-mc146818_set_time.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a8d5f97b17590662e2bed1ee13cfed7ecb560720
Author: Mateusz Jończyk <mat.jonczyk@xxxxx>
Date: Sun Feb 20 10:04:03 2022 +0100
rtc: mc146818-lib: fix locking in mc146818_set_time
[ Upstream commit 811f5559270f25c34c338d6eaa2ece2544c3d3bd ]
In mc146818_set_time(), CMOS_READ(RTC_CONTROL) was performed without the
rtc_lock taken, which is required for CMOS accesses. Fix this.
Nothing in kernel modifies RTC_DM_BINARY, so a separate critical section
is allowed here.
Fixes: dcf257e92622 ("rtc: mc146818: Reduce spinlock section in mc146818_set_time()")
Signed-off-by: Mateusz Jończyk <mat.jonczyk@xxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220220090403.153928-1-mat.jonczyk@xxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c
index 1ca866461d10..3783aaf9dd5a 100644
--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -283,8 +283,10 @@ int mc146818_set_time(struct rtc_time *time)
if (yrs >= 100)
yrs -= 100;
- if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
- || RTC_ALWAYS_BCD) {
+ spin_lock_irqsave(&rtc_lock, flags);
+ save_control = CMOS_READ(RTC_CONTROL);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
sec = bin2bcd(sec);
min = bin2bcd(min);
hrs = bin2bcd(hrs);
