4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vaibhav Jain vaibhav@linux.vnet.ibm.com
[ Upstream commit da96aea0ed177105cb13ee83b328f6c61e061d3f ]
In function __rtc_read_alarm() its possible for an alarm time-stamp to be invalid even after replacing missing components with current time-stamp. The condition 'alarm->time.tm_year < 70' will trigger this case and will cause the call to 'rtc_tm_to_time64(&alarm->time)' return a negative value for variable t_alm.
While handling alarm rollover this negative t_alm (assumed to seconds offset from '1970-01-01 00:00:00') is converted back to rtc_time via rtc_time64_to_tm() which results in this error log with seemingly garbage values:
"rtc rtc0: invalid alarm value: -2-1--1041528741 2005511117:71582844:32"
This error was generated when the rtc driver (rtc-opal in this case) returned an alarm time-stamp of '00-00-00 00:00:00' to indicate that the alarm is disabled. Though I have submitted a separate fix for the rtc-opal driver, this issue may potentially impact other existing/future rtc drivers.
To fix this issue the patch validates the alarm time-stamp just after filling up the missing datetime components and if rtc_valid_tm() still reports it to be invalid then bails out of the function without handling the rollover.
Reported-by: Steve Best sbest@redhat.com Signed-off-by: Vaibhav Jain vaibhav@linux.vnet.ibm.com Signed-off-by: Alexandre Belloni alexandre.belloni@free-electrons.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/rtc/interface.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -227,6 +227,13 @@ int __rtc_read_alarm(struct rtc_device * missing = year; }
+ /* Can't proceed if alarm is still invalid after replacing + * missing fields. + */ + err = rtc_valid_tm(&alarm->time); + if (err) + goto done; + /* with luck, no rollover is needed */ t_now = rtc_tm_to_time64(&now); t_alm = rtc_tm_to_time64(&alarm->time); @@ -278,9 +285,9 @@ int __rtc_read_alarm(struct rtc_device * dev_warn(&rtc->dev, "alarm rollover not handled\n"); }
-done: err = rtc_valid_tm(&alarm->time);
+done: if (err) { dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n", alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,