KCSAN: data-race in timer_clear_idle / trigger_dyntick_cpu.isra.0 (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 05f22368 x86, kcsan: Enable KCSAN for x86
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=14ff8def600000
kernel config: https://syzkaller.appspot.com/x/.config?x=87d111955f40591f
dashboard link: https://syzkaller.appspot.com/bug?extid=00c52c4d7e489dd1799e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [john....@linaro.org linux-...@vger.kernel.org
sb...@kernel.org tg...@linutronix.de el...@google.com]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+00c52c...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in timer_clear_idle / trigger_dyntick_cpu.isra.0

read to 0xffff88812bf1b6e4 of 1 bytes by interrupt on cpu 0:
trigger_dyntick_cpu.isra.0+0x75/0x100 kernel/time/timer.c:577
internal_add_timer kernel/time/timer.c:596 [inline]
add_timer_on+0x186/0x2d0 kernel/time/timer.c:1174
clocksource_watchdog+0x63f/0x760 kernel/time/clocksource.c:297
call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404
expire_timers kernel/time/timer.c:1449 [inline]
__run_timers kernel/time/timer.c:1773 [inline]
__run_timers kernel/time/timer.c:1740 [inline]
run_timer_softirq+0xcb8/0xd20 kernel/time/timer.c:1786
__do_softirq+0x115/0x33f kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0xbb/0xe0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
native_safe_halt+0xe/0x10 arch/x86/kernel/paravirt.c:71
arch_cpu_idle+0x1f/0x30 arch/x86/kernel/process.c:571
default_idle_call+0x1e/0x40 kernel/sched/idle.c:94
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x1af/0x280 kernel/sched/idle.c:263
cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:355

write to 0xffff88812bf1b6e4 of 1 bytes by task 0 on cpu 1:
timer_clear_idle+0x42/0x50 kernel/time/timer.c:1675
tick_nohz_next_event+0x164/0x380 kernel/time/tick-sched.c:708
__tick_nohz_idle_stop_tick kernel/time/tick-sched.c:943 [inline]
tick_nohz_idle_stop_tick+0x3c2/0x670 kernel/time/tick-sched.c:973
cpuidle_idle_call kernel/sched/idle.c:151 [inline]
do_idle+0x1a5/0x280 kernel/sched/idle.c:263
cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:355
start_secondary+0x208/0x260 arch/x86/kernel/smpboot.c:264
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
==================================================================


---
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[Marco Elver]

#syz upstream

On Thursday, December 5, 2019 at 6:45:08 AM UTC+1, syzbot wrote:

Hello,

syzbot found the following crash on:

HEAD commit:    05f22368 x86, kcsan: Enable KCSAN for x86
git tree:       https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=14ff8def600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=87d111955f40591f
dashboard link: https://syzkaller.appspot.com/bug?extid=00c52c4d7e489dd1799e
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
CC:             [john....@linaro.org linux-...@vger.kernel.org  
sb...@kernel.org tg...@linutronix.de el...@google.com]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:

Reported-by: syz...@syzkaller.appspotmail.com

[syzbot]

> #syz upstream

I see the command but can't find the corresponding bug.
Please resend the email to syzbo...@syzkaller.appspotmail.com address
that is the sender of the bug report (also present in the Reported-by tag).

> On Thursday, December 5, 2019 at 6:45:08 AM UTC+1, syzbot wrote:

>> Hello,

>> syzbot found the following crash on:

>> HEAD commit: 05f22368 x86, kcsan: Enable KCSAN for x86
>> git tree: https://github.com/google/ktsan.git kcsan
>> console output: https://syzkaller.appspot.com/x/log.txt?x=14ff8def600000
>> kernel config:
>> https://syzkaller.appspot.com/x/.config?x=87d111955f40591f
>> dashboard link:
>> https://syzkaller.appspot.com/bug?extid=00c52c4d7e489dd1799e
>> compiler: gcc (GCC) 9.0.0 20181231 (experimental)

>> CC: [john....@linaro.org <javascript:>
>> linux-...@vger.kernel.org <javascript:>
>> sb...@kernel.org <javascript:> tg...@linutronix.de <javascript:>
>> el...@google.com <javascript:>]

>> Unfortunately, I don't have any reproducer for this crash yet.

>> IMPORTANT: if you fix the bug, please add the following tag to the
>> commit:

>> Reported-by: syz...@syzkaller.appspotmail.com <javascript:>

>> <javascript:>.

>> syzbot will keep track of this bug report. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

> --
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[syzbot]

> #syz upstream

Your 'upstream' command is accepted, but please keep
syzkaller-upst...@googlegroups.com mailing list in CC next
time. It serves as a history of what happened with each bug report. Thank
you.

> On Thu, 5 Dec 2019 at 06:45, syzbot
> <syzbot+00c52c...@syzkaller.appspotmail.com> wrote:

>> Hello,

>> syzbot found the following crash on:

>> HEAD commit: 05f22368 x86, kcsan: Enable KCSAN for x86
>> git tree: https://github.com/google/ktsan.git kcsan
>> console output: https://syzkaller.appspot.com/x/log.txt?x=14ff8def600000
>> kernel config:
>> https://syzkaller.appspot.com/x/.config?x=87d111955f40591f
>> dashboard link:
>> https://syzkaller.appspot.com/bug?extid=00c52c4d7e489dd1799e
>> compiler: gcc (GCC) 9.0.0 20181231 (experimental)

>> CC: [john....@linaro.org linux-...@vger.kernel.org
>> sb...@kernel.org tg...@linutronix.de el...@google.com]

>> Unfortunately, I don't have any reproducer for this crash yet.

>> IMPORTANT: if you fix the bug, please add the following tag to the
>> commit:

>> Reported-by: syzbot+00c52c...@syzkaller.appspotmail.com

>> syzbot engineers can be reached at syzk...@googlegroups.com.

>> syzbot will keep track of this bug report. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

>> --
>> You received this message because you are subscribed to the Google
>> Groups "syzkaller-upstream-moderation" group.
>> To unsubscribe from this group and stop receiving emails from it, send
>> an email to syzkaller-upstream-m...@googlegroups.com.
>> To view this discussion on the web visit

>> https://groups.google.com/d/msgid/syzkaller-upstream-moderation/000000000000896b8e0598ee6e62%40google.com.