| From foo@baz Mon Apr 9 17:09:24 CEST 2018 |
| From: Vaibhav Jain <vaibhav@linux.vnet.ibm.com> |
| Date: Fri, 19 May 2017 22:18:55 +0530 |
| Subject: rtc: interface: Validate alarm-time before handling rollover |
| |
| 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, |
