From: Mateusz Jończyk mat.jonczyk@o2.pl
commit 811f5559270f25c34c338d6eaa2ece2544c3d3bd upstream.
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@o2.pl Cc: Alessandro Zummo a.zummo@towertech.it Cc: Alexandre Belloni alexandre.belloni@bootlin.com Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Signed-off-by: Alexandre Belloni alexandre.belloni@bootlin.com Link: https://lore.kernel.org/r/20220220090403.153928-1-mat.jonczyk@o2.pl Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/rtc/rtc-mc146818-lib.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/rtc/rtc-mc146818-lib.c +++ b/drivers/rtc/rtc-mc146818-lib.c @@ -176,8 +176,10 @@ int mc146818_set_time(struct rtc_time *t 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);