net.ipv6.conf.syz0.accept_dad = 0
net.ipv6.conf.syz0.router_solicitations = 0
syzkaller login: [   17.385997] ------------[ cut here ]------------
[   17.386510] WARNING: CPU: 0 PID: 2985 at drivers/net/tun.c:1744 tun_get_user+0x2de3/0x36d0
[   17.387564] Kernel panic - not syncing: panic_on_warn set ...
[   17.387564] 
[   17.391094] CPU: 0 PID: 2985 Comm: syzkaller302330 Not tainted 4.14.0-rc5-next-20171018+ #8
executing program
[   17.391914] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[   17.392706] Call Trace:
[   17.392969]  dump_stack+0x194/0x257
[   17.393460]  ? arch_local_irq_restore+0x53/0x53
[   17.393913]  ? vsnprintf+0x1ed/0x1900
[   17.394291]  panic+0x1e4/0x41c
[   17.394602]  ? refcount_error_report+0x214/0x214
[   17.395061]  ? show_regs_print_info+0x65/0x65
[   17.395517]  ? __warn+0x1a9/0x1e0
[   17.395872]  ? tun_get_user+0x2de3/0x36d0
[   17.396277]  __warn+0x1c4/0x1e0
[   17.396716]  ? tun_get_user+0x2de3/0x36d0
[   17.397138]  report_bug+0x211/0x2d0
[   17.397509]  fixup_bug+0x40/0x90
[   17.397855]  do_trap+0x260/0x390
[   17.398212]  do_error_trap+0x120/0x390
[   17.398606]  ? kfree_skbmem+0xe2/0x1d0
[   17.398998]  ? do_trap+0x390/0x390
[   17.399349]  ? __mutex_unlock_slowpath+0xe9/0xac0
[   17.399888]  ? tun_get_user+0x2de3/0x36d0
[   17.400314]  ? wait_for_completion+0x770/0x770
[   17.400773]  ? trace_hardirqs_off_thunk+0x1a/0x1c
[   17.401263]  do_invalid_op+0x1b/0x20
[   17.401637]  invalid_op+0x18/0x20
[   17.401984] RIP: 0010:tun_get_user+0x2de3/0x36d0
[   17.402833] RSP: 0018:ffff880038abf730 EFLAGS: 00010286
[   17.403364] RAX: dffffc0000000000 RBX: ffff88006ca74698 RCX: dffffc0000000000
[   17.404097] RDX: ffffffff87024140 RSI: 0000000000000000 RDI: 0000000000000282
[   17.404777] RBP: ffff880038abfae0 R08: 0000000000000001 R09: 0000000000000000
[   17.405466] R10: ffffffff870692e0 R11: 0000000000000000 R12: ffff88003b6afcc0
[   17.406152] R13: ffff88006ca74708 R14: 0000000000000003 R15: ffff88006bf00cc0
[   17.406873]  ? __thp_get_unmapped_area+0x130/0x130
[   17.407390]  ? tun_build_skb.isra.48+0x16e0/0x16e0
[   17.407934]  ? kmem_cache_alloc+0x12e/0x760
[   17.408336]  ? do_mmap+0x69b/0xd40
[   17.408692]  ? vm_mmap_pgoff+0x1de/0x280
[   17.409100]  ? SyS_mmap_pgoff+0x23b/0x5f0
[   17.409511]  ? SyS_mmap+0x16/0x20
[   17.409844]  ? entry_SYSCALL_64_fastpath+0x1f/0xbe
[   17.410326]  ? trace_hardirqs_on+0xd/0x10
[   17.410728]  ? check_noncircular+0x20/0x20
[   17.411150]  ? tun_get+0x1ab/0x2e0
[   17.411499]  ? lock_release+0xa40/0xa40
[   17.411939]  ? __lock_is_held+0xb6/0x140
[   17.412345]  ? tun_get+0x1d4/0x2e0
[   17.412688]  ? tun_chr_close+0x60/0x60
[   17.413060]  ? __check_object_size+0x25d/0x4f0
[   17.413503]  ? rcu_note_context_switch+0x710/0x710
[   17.413980]  tun_chr_write_iter+0xb9/0x160
[   17.414387]  do_iter_readv_writev+0x525/0x7f0
[   17.414834]  ? vfs_dedupe_file_range+0x8f0/0x8f0
[   17.415321]  ? rw_verify_area+0xe5/0x2b0
[   17.415723]  do_iter_write+0x154/0x540
[   17.416227]  ? dup_iter+0x260/0x260
[   17.416601]  ? handle_mm_fault+0x410/0x8d0
[   17.417037]  ? __do_page_fault+0x31e/0xd60
[   17.417453]  vfs_writev+0x18a/0x340
[   17.417798]  ? __fget_light+0x297/0x380
[   17.418182]  ? vfs_iter_write+0xb0/0xb0
[   17.418561]  ? __do_page_fault+0x3d6/0xd60
[   17.418962]  ? down_read_killable+0x180/0x180
[   17.419398]  ? mm_fault_error+0x2c0/0x2c0
[   17.419852]  ? vm_mmap_pgoff+0x13b/0x280
[   17.420264]  ? __fdget_pos+0x130/0x190
[   17.420642]  ? do_page_fault+0xee/0x720
[   17.421027]  ? __fdget_raw+0x20/0x20
[   17.421387]  ? __do_page_fault+0xd60/0xd60
[   17.421801]  do_writev+0xfc/0x2a0
[   17.422132]  ? do_writev+0xfc/0x2a0
[   17.422483]  ? vfs_writev+0x340/0x340
[   17.422844]  ? entry_SYSCALL_64_fastpath+0x5/0xbe
[   17.423305]  ? trace_hardirqs_on_caller+0x421/0x5c0
[   17.423786]  SyS_writev+0x27/0x30
[   17.424843]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   17.425312] RIP: 0033:0x43a347
[   17.425629] RSP: 002b:00007fff7a142508 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
[   17.426392] RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 000000000043a347
[   17.427102] RDX: 0000000000000003 RSI: 00007fff7a142520 RDI: 0000000000000003
[   17.427878] RBP: 0000000000000082 R08: 0000000000000001 R09: 0000000000000002
[   17.428599] R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
[   17.429296] R13: 0000000000402960 R14: 00000000004029f0 R15: 0000000000000000
[   17.431873] Dumping ftrace buffer:
[   17.432312]    (ftrace buffer empty)
[   17.432676] Kernel Offset: disabled
[   17.433037] Rebooting in 86400 seconds..