syzbot

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BUG: KMSAN: uninit-value in __queue_work+0x1b2/0x1f00 kernel/workqueue.c:1387
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.17.0-rc5+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x149/0x260 mm/kmsan/kmsan.c:1084
 __msan_warning_32+0x6e/0xc0 mm/kmsan/kmsan_instr.c:685
 __queue_work+0x1b2/0x1f00 kernel/workqueue.c:1387
 delayed_work_timer_fn+0xa1/0xd0 kernel/workqueue.c:1500
 call_timer_fn+0x280/0x5d0 kernel/time/timer.c:1326
 expire_timers kernel/time/timer.c:1359 [inline]
 __run_timers+0xdec/0x11b0 kernel/time/timer.c:1666
 run_timer_softirq+0x43/0x70 kernel/time/timer.c:1692
 __do_softirq+0x592/0x979 kernel/softirq.c:285
 invoke_softirq kernel/softirq.c:365 [inline]
 irq_exit+0x202/0x240 kernel/softirq.c:405
 exiting_irq+0xe/0x10 arch/x86/include/asm/apic.h:525
 smp_apic_timer_interrupt+0x64/0x90 arch/x86/kernel/apic/apic.c:1055
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
 </IRQ>
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:55 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:97 [inline]
RIP: 0010:default_idle+0x20b/0x3e0 arch/x86/kernel/process.c:354
RSP: 0018:ffffffff8ac0fd90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff8801fd432a78 RBX: 0000000000000000 RCX: ffff880000000000
RDX: ffff8801fd032a78 RSI: aaaaaaaaaaaab000 RDI: ffffea0000000000
RBP: ffffffff8ac0fdc8 R08: 0000000001080020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff89fdb110 R12: ffffffff8ac0fe2f
R13: ffffffff8ac372c0 R14: ffffffff8ac0fe2c R15: ffffffff8ac37b98
 arch_cpu_idle+0x26/0x30 arch/x86/kernel/process.c:345
 default_idle_call kernel/sched/idle.c:93 [inline]
 cpuidle_idle_call kernel/sched/idle.c:153 [inline]
 do_idle+0x36d/0x830 kernel/sched/idle.c:262
 cpu_startup_entry+0x45/0x50 kernel/sched/idle.c:368
 rest_init+0x1c1/0x1f0 init/main.c:442
 start_kernel+0x1110/0x1120 init/main.c:739
 x86_64_start_reservations arch/x86/kernel/head64.c:454 [inline]
 x86_64_start_kernel+0xe4/0xf0 arch/x86/kernel/head64.c:435
 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:294 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:685
 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:529
 __queue_delayed_work+0x3d1/0x450 kernel/workqueue.c:1527
 queue_delayed_work_on+0x1e8/0x210 kernel/workqueue.c:1558
 queue_delayed_work include/linux/workqueue.h:526 [inline]
 schedule_delayed_work include/linux/workqueue.h:627 [inline]
 linkwatch_schedule_work net/core/link_watch.c:140 [inline]
 linkwatch_fire_event+0xa5d/0xbf0 net/core/link_watch.c:251
 netif_carrier_off+0x10b/0x150 net/sched/sch_generic.c:542
 __tun_detach+0x23c3/0x2790 drivers/net/tun.c:733
 tun_detach drivers/net/tun.c:752 [inline]
 tun_chr_close+0xda/0x1c0 drivers/net/tun.c:3251
 __fput+0x458/0xa30 fs/file_table.c:209
 ____fput+0x37/0x40 fs/file_table.c:243
 task_work_run+0x22e/0x2b0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x110e/0x3930 kernel/exit.c:867
 do_group_exit+0x1a0/0x360 kernel/exit.c:970
 get_signal+0x1405/0x1ec0 kernel/signal.c:2482
 do_signal+0xb8/0x1d20 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:162 [inline]
 prepare_exit_to_usermode+0x271/0x3a0 arch/x86/entry/common.c:196
 syscall_return_slowpath+0xe9/0x710 arch/x86/entry/common.c:265
 do_syscall_64+0x1ad/0x230 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Local variable description: ----tlb.i@ldt_arch_exit_mmap
Variable was created at:
 ldt_arch_exit_mmap+0x46/0x160 arch/x86/kernel/ldt.c:302
 arch_exit_mmap arch/x86/include/asm/mmu_context.h:245 [inline]
 exit_mmap+0x410/0x980 mm/mmap.c:3094
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