WARNING: CPU: 3 PID: 2992 at drivers/net/tun.c:1744 tun_get_user+0x2de3/0x36d0 drivers/net/tun.c:1743
Kernel panic - not syncing: panic_on_warn set ...

CPU: 3 PID: 2992 Comm: syzkaller046060 Not tainted 4.14.0-rc5-next-20171018+ #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1c4/0x1e0 kernel/panic.c:546
 report_bug+0x211/0x2d0 lib/bug.c:183
 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:177
 do_trap_no_signal arch/x86/kernel/traps.c:211 [inline]
 do_trap+0x260/0x390 arch/x86/kernel/traps.c:260
 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:297
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:310
 invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
RIP: 0010:tun_get_user+0x2de3/0x36d0 drivers/net/tun.c:1743
RSP: 0018:ffff880039c6f730 EFLAGS: 00010286
RAX: dffffc0000000000 RBX: ffff88006afa8998 RCX: dffffc0000000000
RDX: ffffffff87024140 RSI: 0000000000000000 RDI: 0000000000000282
RBP: ffff880039c6fae0 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff870692e0 R11: 0000000000000000 R12: ffff880067fca500
R13: ffff88006afa8a08 R14: 0000000000000000 R15: ffff880067758e40
 tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1792
 call_write_iter include/linux/fs.h:1770 [inline]
 do_iter_readv_writev+0x525/0x7f0 fs/read_write.c:673
 do_iter_write+0x154/0x540 fs/read_write.c:952
 vfs_writev+0x18a/0x340 fs/read_write.c:997
 do_writev+0xfc/0x2a0 fs/read_write.c:1032
 SYSC_writev fs/read_write.c:1105 [inline]
 SyS_writev+0x27/0x30 fs/read_write.c:1102
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x439dc7
RSP: 002b:00007ffca3c55a18 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 0000000000439dc7
RDX: 0000000000000002 RSI: 00007ffca3c55a30 RDI: 0000000000000003
RBP: 0000000000000082 R08: 000000000000003e R09: 0000000000000004
R10: 00000000aaaaaaaa R11: 0000000000000246 R12: 0000000000000000
R13: 00000000004023e0 R14: 0000000000402470 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..