linux-kernel - [tip:timers/core] alarmtimer: Init nanosleep alarm timer on stack

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <tip-5110c037daf437dbc163be5e9be18c8412a798e6@git.kernel.org>
Date:   Thu, 29 Mar 2018 06:22:11 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, tglx@...utronix.de, linux-kernel@...r.kernel.org,
        john.stultz@...aro.org, mingo@...nel.org
Subject: [tip:timers/core] alarmtimer: Init nanosleep alarm timer on stack

Commit-ID:  5110c037daf437dbc163be5e9be18c8412a798e6
Gitweb:     https://git.kernel.org/tip/5110c037daf437dbc163be5e9be18c8412a798e6
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Mon, 26 Mar 2018 15:29:57 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 29 Mar 2018 15:17:38 +0200

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@...kaller.appspotmail.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: John Stultz <john.stultz@...aro.org>
Cc: syzkaller-bugs@...glegroups.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..bc05b28e16c8 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
@@ -335,16 +346,21 @@ 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);
 
+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_start - Sets an absolute alarm to fire
  * @alarm: ptr to alarm to set
@@ -719,6 +735,8 @@ 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;
 
@@ -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 */