• Vaibhav Jain's avatar
    rtc: interface: Validate alarm-time before handling rollover · da96aea0
    Vaibhav Jain authored
    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
    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: default avatarSteve Best <sbest@redhat.com>
    Signed-off-by: default avatarVaibhav Jain <vaibhav@linux.vnet.ibm.com>
    Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
interface.c 25.3 KB