kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 2987 Comm: syzkaller761622 Not tainted 4.14.0-rc5-mm1+ #18
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d1c96740 task.stack: ffff8801d1d38000
RIP: 0010:__read_once_size include/linux/compiler.h:276 [inline]
RIP: 0010:hrtimer_active+0x211/0x410 kernel/time/hrtimer.c:1142
RSP: 0018:ffff8801d1d3f3f0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 1ffff1003a3a7eab RCX: ffffffff815ef93f
RDX: 0000000000000000 RSI: ffffffff85b376e0 RDI: ffff8801d49e72e0
RBP: ffff8801d1d3f530 R08: ffffffff83f9e367 R09: 0000000000000004
R10: ffff8801d1d3f898 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffed003a3a7e89 R15: dffffc0000000000
FS:  00000000020c0880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3aed9e3518 CR3: 00000001cee83000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 hrtimer_try_to_cancel+0x91/0x5c0 kernel/time/hrtimer.c:1006
 hrtimer_cancel+0x22/0x40 kernel/time/hrtimer.c:1032
 napi_disable+0x87/0xa0 net/core/dev.c:5551
 tun_napi_disable drivers/net/tun.c:290 [inline]
 __tun_detach+0xe26/0x1570 drivers/net/tun.c:617
 tun_detach drivers/net/tun.c:664 [inline]
 tun_chr_close+0x44/0x60 drivers/net/tun.c:2835
 __fput+0x327/0x7e0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:112
 exit_task_work include/linux/task_work.h:21 [inline]
 do_exit+0x9b5/0x1ad0 kernel/exit.c:869
 do_group_exit+0x149/0x400 kernel/exit.c:972
 SYSC_exit_group kernel/exit.c:983 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:981
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x442aa8
RSP: 002b:00007fffeb2529c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442aa8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 0000000000000082 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000000000 R11: 0000000000000246 R12: 74656e2f7665642f
R13: 0000000000401b80 R14: 0000000000000000 R15: 0000000000000000
Code: c6 00 00 48 8b 85 d8 fe ff ff 48 c1 e8 03 42 80 3c 38 00 0f 85 f2 01 00 00 48 8b 85 e8 fe ff ff 4c 8b 60 30 4c 89 e0 48 c1 e8 03 <42> 80 3c 38 00 0f 85 c8 01 00 00 48 8b 85 f0 fe ff ff 49 8b 1c 
RIP: __read_once_size include/linux/compiler.h:276 [inline] RSP: ffff8801d1d3f3f0
RIP: hrtimer_active+0x211/0x410 kernel/time/hrtimer.c:1142 RSP: ffff8801d1d3f3f0
---[ end trace f9c7f66be8deaae6 ]---