From bd03143007eb9b03a7f2316c677780561b68ba2a Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 26 Mar 2018 15:29:57 +0200 Subject: [PATCH] alarmtimer: Init nanosleep alarm timer on stack syszbot reported the following debugobjects splat: ODEBUG: object is on stack, but not annotated WARNING: CPU: 0 PID: 4185 at lib/debugobjects.c:328 RIP: 0010:debug_object_is_on_stack lib/debugobjects.c:327 [inline] debug_object_init+0x17/0x20 lib/debugobjects.c:391 debug_hrtimer_init kernel/time/hrtimer.c:410 [inline] debug_init kernel/time/hrtimer.c:458 [inline] hrtimer_init+0x8c/0x410 kernel/time/hrtimer.c:1259 alarm_init kernel/time/alarmtimer.c:339 [inline] alarm_timer_nsleep+0x164/0x4d0 kernel/time/alarmtimer.c:787 SYSC_clock_nanosleep kernel/time/posix-timers.c:1226 [inline] SyS_clock_nanosleep+0x235/0x330 kernel/time/posix-timers.c:1204 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 This happens because the hrtimer for the alarm nanosleep is on stack, but the code does not use the proper debug objects initialization. Split out the code for the allocated use cases and invoke hrtimer_init_on_stack() for the nanosleep related functions. Reported-by: syzbot+a3e0726462b2e346a31d@syzkaller.appspotmail.com Signed-off-by: Thomas Gleixner Cc: John Stultz Cc: syzkaller-bugs@googlegroups.com Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1803261528270.1585@nanos.tec.linutronix.de --- kernel/time/alarmtimer.c | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-) diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index ec09ce9a6012..639321bf2e39 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -326,6 +326,17 @@ static int alarmtimer_resume(struct device *dev) } #endif +static void +__alarm_init(struct alarm *alarm, enum alarmtimer_type type, + enum alarmtimer_restart (*function)(struct alarm *, ktime_t)) +{ + timerqueue_init(&alarm->node); + alarm->timer.function = alarmtimer_fired; + alarm->function = function; + alarm->type = type; + alarm->state = ALARMTIMER_STATE_INACTIVE; +} + /** * alarm_init - Initialize an alarm structure * @alarm: ptr to alarm to be initialized @@ -335,13 +346,9 @@ static int alarmtimer_resume(struct device *dev) void alarm_init(struct alarm *alarm, enum alarmtimer_type type, enum alarmtimer_restart (*function)(struct alarm *, ktime_t)) { - timerqueue_init(&alarm->node); hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid, - HRTIMER_MODE_ABS); - alarm->timer.function = alarmtimer_fired; - alarm->function = function; - alarm->type = type; - alarm->state = ALARMTIMER_STATE_INACTIVE; + HRTIMER_MODE_ABS); + __alarm_init(alarm, type, function); } EXPORT_SYMBOL_GPL(alarm_init); @@ -719,6 +726,8 @@ static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp, __set_current_state(TASK_RUNNING); + destroy_hrtimer_on_stack(&alarm->timer); + if (!alarm->data) return 0; @@ -740,6 +749,15 @@ static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp, return -ERESTART_RESTARTBLOCK; } +static void +alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type, + enum alarmtimer_restart (*function)(struct alarm *, ktime_t)) +{ + hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid, + HRTIMER_MODE_ABS); + __alarm_init(alarm, type, function); +} + /** * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep * @restart: ptr to restart block @@ -752,7 +770,7 @@ static long __sched alarm_timer_nsleep_restart(struct restart_block *restart) ktime_t exp = restart->nanosleep.expires; struct alarm alarm; - alarm_init(&alarm, type, alarmtimer_nsleep_wakeup); + alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup); return alarmtimer_do_nsleep(&alarm, exp, type); } @@ -784,7 +802,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags, if (!capable(CAP_WAKE_ALARM)) return -EPERM; - alarm_init(&alarm, type, alarmtimer_nsleep_wakeup); + alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup); exp = timespec64_to_ktime(*tsreq); /* Convert (if necessary) to absolute time */