From c254bcd7231a3eeafc453f6ee3a483a2e7ff486e Mon Sep 17 00:00:00 2001 From: Victor Ding Date: Fri, 14 Aug 2020 19:17:30 +1000 Subject: [PATCH] rtc: cmos: zero-init wkalrm when reading from CMOS cmos_read_alarm() may leave certain fields of a struct rtc_wkalrm untouched; therefore, these fields contain garbage if not properly initialized, leading to inconsistent values when converting into time64_t. This patch to zero initialize the struct before calling cmos_read_alarm(). Note that this patch is not intended to produce a correct time64_t, it is only to produce a consistent value. In the case of suspend/resume, a correct time64_t is not necessary; a consistent value is sufficient to correctly perform an equality test for t_current_expires and t_saved_expires. Logic to deduce a correct time64_t is expensive and hence should be avoided. Signed-off-by: Victor Ding Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20200814191654.v2.1.Iaf7638a2f2a87ff68d85fcb8dec615e41340c97f@changeid --- drivers/rtc/rtc-cmos.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index bcc96ab..c633319c 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -1006,6 +1006,7 @@ static int cmos_suspend(struct device *dev) enable_irq_wake(cmos->irq); } + memset(&cmos->saved_wkalrm, 0, sizeof(struct rtc_wkalrm)); cmos_read_alarm(dev, &cmos->saved_wkalrm); dev_dbg(dev, "suspend%s, ctrl %02x\n", @@ -1054,6 +1055,7 @@ static void cmos_check_wkalrm(struct device *dev) return; } + memset(¤t_alarm, 0, sizeof(struct rtc_wkalrm)); cmos_read_alarm(dev, ¤t_alarm); t_current_expires = rtc_tm_to_time64(¤t_alarm.time); t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time); -- 2.7.4