Air Icy reported:
UBSAN: Undefined behaviour in kernel/time/alarmtimer.c:811:7
signed integer overflow:
1529859276030040771 + 9223372036854775807 cannot be represented in type 'long long int'
Call Trace:
alarm_timer_nsleep+0x44c/0x510 kernel/time/alarmtimer.c:811
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1235 [inline]
__se_sys_clock_nanosleep kernel/time/posix-timers.c:1213 [inline]
__x64_sys_clock_nanosleep+0x326/0x4e0 kernel/time/posix-timers.c:1213
do_syscall_64+0xb8/0x3a0 arch/x86/entry/common.c:290
alarm_timer_nsleep() uses ktime_add() to add the current time and the
relative expiry value. ktime_add() has no sanity checks so the addition
can overflow when the relative timeout is large enough.
Use ktime_add_safe() which has the necessary sanity checks in place and
limits the result to the valid range.
Fixes: 9a7adcf5c6 ("timers: Posix interface for alarm-timers")
Reported-by: Team OWL337 <icytxw@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1807020926360.1595@nanos.tec.linutronix.de
The posix timer ti_overrun handling is broken because the forwarding
functions can return a huge number of overruns which does not fit in an
int. As a consequence timer_getoverrun(2) and siginfo::si_overrun can turn
into random number generators.
As a first step to address that let the timer_forward() callbacks return
the full 64 bit value.
Cast it to (int) temporarily until k_itimer::ti_overrun is converted to
64bit and the conversion to user space visible values is sanitized.
Reported-by: Team OWL337 <icytxw@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Link: https://lkml.kernel.org/r/20180626132704.922098090@linutronix.de
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 <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: syzkaller-bugs@googlegroups.com
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1803261528270.1585@nanos.tec.linutronix.de
Currently the alarmtimer registers a wake-up source unconditionally,
regardless of the system having a (wake-up capable) RTC or not.
Hence the alarmtimer will always show up in
/sys/kernel/debug/wakeup_sources, even if it is not available, and thus
cannot be a wake-up source.
To fix this, postpone registration until a wake-up capable RTC device is
added.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Usage of these apis and their compat versions makes
the syscalls: clock_nanosleep and nanosleep and
their compat implementations simpler.
This is a preparatory patch to isolate data conversions to
struct timespec64 at userspace boundaries. This helps contain
the changes needed to transition to new y2038 safe types.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Turn restart_block.nanosleep.{rmtp,compat_rmtp} into a tagged union (kind =
1 -> native, kind = 2 -> compat, kind = 0 -> nothing) and make the places
doing actual copyout handle compat as well as native (that will become a
helper in the next commit). Result: compat wrappers, messing with
reassignments, etc. are gone.
[ tglx: Folded in a variant of Peter Zijlstras enum patch ]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-6-viro@ZenIV.linux.org.uk
The alarmtimer nanosleep() implementation can be simplified by moving the
copy out of the remaining time to alarmtimer_do_nsleep() which is shared
between the real nanosleep function and the restart function.
The pointer to the timespec64 which is updated has to be stored in the
restart block anyway. Instead of storing it only in the restart case, store
it before calling alarmtimer_do_nsleep() and copy the remaining time in the
signal exit path.
[ tglx: Added changelog ]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-2-viro@ZenIV.linux.org.uk
The alarmtimer code has another source of potentially rearming itself too
fast. Interval timers with a very samll interval have a similar CPU hog
effect as the previously fixed overflow issue.
The reason is that alarmtimers do not implement the normal protection
against this kind of problem which the other posix timer use:
timer expires -> queue signal -> deliver signal -> rearm timer
This scheme brings the rearming under scheduler control and prevents
permanently firing timers which hog the CPU.
Bringing this scheme to the alarm timer code is a major overhaul because it
lacks all the necessary mechanisms completely.
So for a quick fix limit the interval to one jiffie. This is not
problematic in practice as alarmtimers are usually backed by an RTC for
suspend which have 1 second resolution. It could be therefor argued that
the resolution of this clock should be set to 1 second in general, but
that's outside the scope of this fix.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kostya Serebryany <kcc@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170530211655.896767100@linutronix.de
Andrey reported a alartimer related RCU stall while fuzzing the kernel with
syzkaller.
The reason for this is an overflow in ktime_add() which brings the
resulting time into negative space and causes immediate expiry of the
timer. The following rearm with a small interval does not bring the timer
back into positive space due to the same issue.
This results in a permanent firing alarmtimer which hogs the CPU.
Use ktime_add_safe() instead which detects the overflow and clamps the
result to KTIME_SEC_MAX.
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kostya Serebryany <kcc@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170530211655.802921648@linutronix.de
Some freezer related variables are only used when either CONFIG_POSIX_TIMER
or CONFIG_RTC_CLASS are enabled. Hide them when both are off.
Fixes: d3ba5a9a34 ("posix-timers: Make posix_clocks immutable")
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Helwig <hch@lst.de>
There are no more modular users providing a posix clock. The register
function is now pointless so the posix clock array can be initialized
statically at compile time and the array including the various k_clock
structs can be marked 'const'.
Inspired by changes in the Grsecurity patch set, but done proper.
[ tglx: Massaged changelog and fixed the POSIX_TIMER=n case ]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Dimitri Sivanich <sivanich@hpe.com>
Link: http://lkml.kernel.org/r/20170526090311.3377-3-hch@lst.de
Thomas Gleixner
Alexandre Belloni
Geert Uytterhoeven
Deepa Dinamani
Al Viro
Christoph Hellwig