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979515c564
linux/kernel/time
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Vegard Nossum 979515c564 time: Avoid undefined behaviour in ktime_add_safe() 
I ran into this:

    ================================================================================
    UBSAN: Undefined behaviour in kernel/time/hrtimer.c:310:16
    signed integer overflow:
    9223372036854775807 + 50000 cannot be represented in type 'long long int'
    CPU: 2 PID: 4798 Comm: trinity-c2 Not tainted 4.8.0-rc1+ #91
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
     0000000000000000 ffff88010ce6fb88 ffffffff82344740 0000000041b58ab3
     ffffffff84f97a20 ffffffff82344694 ffff88010ce6fbb0 ffff88010ce6fb60
     000000000000c350 ffff88010ce6f968 dffffc0000000000 ffffffff857bc320
    Call Trace:
     [<ffffffff82344740>] dump_stack+0xac/0xfc
     [<ffffffff82344694>] ? _atomic_dec_and_lock+0xc4/0xc4
     [<ffffffff8242df78>] ubsan_epilogue+0xd/0x8a
     [<ffffffff8242e6b4>] handle_overflow+0x202/0x23d
     [<ffffffff8242e4b2>] ? val_to_string.constprop.6+0x11e/0x11e
     [<ffffffff8236df71>] ? timerqueue_add+0x151/0x410
     [<ffffffff81485c48>] ? hrtimer_start_range_ns+0x3b8/0x1380
     [<ffffffff81795631>] ? memset+0x31/0x40
     [<ffffffff8242e6fd>] __ubsan_handle_add_overflow+0xe/0x10
     [<ffffffff81488ac9>] hrtimer_nanosleep+0x5d9/0x790
     [<ffffffff814884f0>] ? hrtimer_init_sleeper+0x80/0x80
     [<ffffffff813a9ffb>] ? __might_sleep+0x5b/0x260
     [<ffffffff8148be10>] common_nsleep+0x20/0x30
     [<ffffffff814906c7>] SyS_clock_nanosleep+0x197/0x210
     [<ffffffff81490530>] ? SyS_clock_getres+0x150/0x150
     [<ffffffff823c7113>] ? __this_cpu_preempt_check+0x13/0x20
     [<ffffffff8162ef60>] ? __context_tracking_exit.part.3+0x30/0x1b0
     [<ffffffff81490530>] ? SyS_clock_getres+0x150/0x150
     [<ffffffff81007bd3>] do_syscall_64+0x1b3/0x4b0
     [<ffffffff845f85aa>] entry_SYSCALL64_slow_path+0x25/0x25
    ================================================================================

Add a new ktime_add_unsafe() helper which doesn't check for overflow, but
doesn't throw a UBSAN warning when it does overflow either.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2016-08-31 14:43:36 -07:00
..
alarmtimer.c alarmtimer: Fix comments describing structure fields 2016-06-20 12:47:09 -07:00
clockevents.c clockevents: Make clockevents_subsys static 2016-07-19 10:48:06 +02:00
clocksource.c clocksource: Defer override invalidation unless clock is unstable 2016-08-31 14:43:33 -07:00
hrtimer.c time: Avoid undefined behaviour in ktime_add_safe() 2016-08-31 14:43:36 -07:00
itimer.c itimers: Handle relative timers with CONFIG_TIME_LOW_RES proper 2016-01-17 11:13:55 +01:00
jiffies.c jiffies: Use CLOCKSOURCE_MASK instead of constant 2016-02-27 08:55:31 +01:00
Kconfig rcu: Drop RCU_USER_QS in favor of NO_HZ_FULL 2015-07-06 13:52:18 -07:00
Makefile time: Remove development rules from Kbuild/Makefile 2015-07-01 09:57:35 +02:00
ntp_internal.h ntp: Fix second_overflow's input parameter type to be 64bits 2015-12-16 16:50:56 -08:00
ntp.c ntp: Fix ADJ_SETOFFSET being used w/ ADJ_NANO 2016-01-22 12:01:42 +01:00
posix-clock.c posix-clock: Fix return code on the poll method's error path 2015-12-29 11:33:06 +01:00
posix-cpu-timers.c posix_cpu_timer: Exit early when process has been reaped 2016-07-11 17:20:12 +02:00
posix-timers.c posix-timers: Handle relative timers with CONFIG_TIME_LOW_RES proper 2016-01-17 11:13:55 +01:00
sched_clock.c
test_udelay.c time: Avoid timespec in udelay_test 2016-06-20 12:47:26 -07:00
tick-broadcast-hrtimer.c tick/broadcast-hrtimer: Set name of the ce_broadcast_hrtimer 2016-07-05 17:02:19 +02:00
tick-broadcast.c tick: Move the export of tick_broadcast_oneshot_control to the proper place 2015-07-14 12:01:04 +02:00
tick-common.c clockevents: Remove unused set_mode() callback 2015-09-14 11:00:55 +02:00
tick-internal.h timers: Forward the wheel clock whenever possible 2016-07-07 10:35:11 +02:00
tick-oneshot.c clockevents: Provide functions to set and get the state 2015-06-02 14:40:47 +02:00
tick-sched.c tick/nohz: Optimize nohz idle enter 2016-07-19 13:48:24 +02:00
tick-sched.h timers/nohz: Convert tick dependency mask to atomic_t 2016-03-29 11:52:11 +02:00
time.c time: Avoid undefined behaviour in timespec64_add_safe() 2016-08-31 14:43:35 -07:00
timeconst.bc timeconst: Update path in comment 2015-10-26 10:06:06 +09:00
timeconv.c time: Add time64_to_tm() 2016-06-20 12:47:15 -07:00
timecounter.c
timekeeping_debug.c timekeeping: Prints the amounts of time spent during suspend 2016-08-31 14:43:34 -07:00
timekeeping_internal.h clocksource: Make clocksource validation work for all clocksources 2015-12-19 15:59:57 +01:00
timekeeping.c timekeeping: Avoid taking lock in NMI path with CONFIG_DEBUG_TIMEKEEPING 2016-08-24 09:34:31 +02:00
timekeeping.h
timer_list.c hrtimer: Handle remaining time proper for TIME_LOW_RES 2016-01-17 11:13:55 +01:00
timer_stats.c timer: Avoid using timespec 2016-06-20 12:47:33 -07:00
timer.c timers: Fix get_next_timer_interrupt() computation 2016-08-09 09:31:55 +02:00