net.ipv6.conf.syz0.accept_dad = 0
net.ipv6.conf.syz0.router_solicitations = 0
syzkaller login: [   16.830289] ------------[ cut here ]------------
[   16.830670] WARNING: CPU: 3 PID: 2992 at drivers/net/tun.c:1744 tun_get_user+0x2de3/0x36d0
[   16.831311] Kernel panic - not syncing: panic_on_warn set ...
[   16.831311] 
[   16.831881] CPU: 3 PID: 2992 Comm: syzkaller046060 Not tainted 4.14.0-rc5-next-20171018+ #8
[   16.832727] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[   16.833321] Call Trace:
[   16.833524]  dump_stack+0x194/0x257
[   16.833789]  ? arch_local_irq_restore+0x53/0x53
[   16.834137]  ? vsnprintf+0x1ed/0x1900
[   16.834454]  panic+0x1e4/0x41c
[   16.834691]  ? refcount_error_report+0x214/0x214
[   16.835037]  ? show_regs_print_info+0x65/0x65
[   16.835410]  ? __warn+0x1a9/0x1e0
executing program
[   16.835706]  ? tun_get_user+0x2de3/0x36d0
[   16.836622]  __warn+0x1c4/0x1e0
[   16.836930]  ? tun_get_user+0x2de3/0x36d0
[   16.837435]  report_bug+0x211/0x2d0
[   16.837801]  fixup_bug+0x40/0x90
[   16.838137]  do_trap+0x260/0x390
[   16.838482]  do_error_trap+0x120/0x390
[   16.838883]  ? kfree_skbmem+0xe2/0x1d0
[   16.839269]  ? do_trap+0x390/0x390
[   16.839615]  ? __mutex_unlock_slowpath+0xe9/0xac0
[   16.844112]  ? tun_get_user+0x2de3/0x36d0
[   16.844503]  ? wait_for_completion+0x770/0x770
[   16.844941]  ? trace_hardirqs_off_thunk+0x1a/0x1c
[   16.845412]  do_invalid_op+0x1b/0x20
[   16.845781]  invalid_op+0x18/0x20
[   16.846116] RIP: 0010:tun_get_user+0x2de3/0x36d0
[   16.846586] RSP: 0018:ffff880039c6f730 EFLAGS: 00010286
[   16.847115] RAX: dffffc0000000000 RBX: ffff88006afa8998 RCX: dffffc0000000000
[   16.847826] RDX: ffffffff87024140 RSI: 0000000000000000 RDI: 0000000000000282
[   16.852501] RBP: ffff880039c6fae0 R08: 0000000000000001 R09: 0000000000000000
[   16.853198] R10: ffffffff870692e0 R11: 0000000000000000 R12: ffff880067fca500
[   16.853881] R13: ffff88006afa8a08 R14: 0000000000000000 R15: ffff880067758e40
[   16.854582]  ? __thp_get_unmapped_area+0x130/0x130
[   16.855075]  ? tun_build_skb.isra.48+0x16e0/0x16e0
[   16.855551]  ? kmem_cache_alloc+0x12e/0x760
[   16.855962]  ? do_mmap+0x69b/0xd40
[   16.856318]  ? vm_mmap_pgoff+0x1de/0x280
[   16.856734]  ? SyS_mmap_pgoff+0x23b/0x5f0
[   16.857164]  ? SyS_mmap+0x16/0x20
[   16.857512]  ? entry_SYSCALL_64_fastpath+0x1f/0xbe
[   16.858012]  ? trace_hardirqs_on+0xd/0x10
[   16.858403]  ? check_noncircular+0x20/0x20
[   16.858815]  ? tun_get+0x1ab/0x2e0
[   16.859155]  ? lock_release+0xa40/0xa40
[   16.859527]  ? __lock_is_held+0xb6/0x140
[   16.859918]  ? tun_get+0x1d4/0x2e0
[   16.860595]  ? tun_chr_close+0x60/0x60
[   16.860942]  ? __check_object_size+0x25d/0x4f0
[   16.861347]  ? rcu_note_context_switch+0x710/0x710
[   16.861786]  tun_chr_write_iter+0xb9/0x160
[   16.862161]  do_iter_readv_writev+0x525/0x7f0
[   16.862561]  ? vfs_dedupe_file_range+0x8f0/0x8f0
[   16.862986]  ? rw_verify_area+0xe5/0x2b0
[   16.863346]  do_iter_write+0x154/0x540
[   16.863688]  ? dup_iter+0x260/0x260
[   16.864062]  ? handle_mm_fault+0x410/0x8d0
[   16.864433]  ? __do_page_fault+0x31e/0xd60
[   16.864812]  vfs_writev+0x18a/0x340
[   16.865130]  ? __fget_light+0x297/0x380
[   16.865487]  ? vfs_iter_write+0xb0/0xb0
[   16.865842]  ? __do_page_fault+0x3d6/0xd60
[   16.866217]  ? down_read_killable+0x180/0x180
[   16.866623]  ? mm_fault_error+0x2c0/0x2c0
[   16.866994]  ? vm_mmap_pgoff+0x13b/0x280
[   16.867362]  ? __fdget_pos+0x130/0x190
[   16.867706]  ? do_page_fault+0xee/0x720
[   16.868290]  ? __fdget_raw+0x20/0x20
[   16.868630]  ? __do_page_fault+0xd60/0xd60
[   16.869040]  do_writev+0xfc/0x2a0
[   16.869363]  ? do_writev+0xfc/0x2a0
[   16.869642]  ? vfs_writev+0x340/0x340
[   16.869923]  ? entry_SYSCALL_64_fastpath+0x5/0xbe
[   16.870292]  ? trace_hardirqs_on_caller+0x421/0x5c0
[   16.870664]  SyS_writev+0x27/0x30
[   16.870922]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   16.871295] RIP: 0033:0x439dc7
[   16.871523] RSP: 002b:00007ffca3c55a18 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
[   16.872536] RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 0000000000439dc7
[   16.873164] RDX: 0000000000000002 RSI: 00007ffca3c55a30 RDI: 0000000000000003
[   16.873765] RBP: 0000000000000082 R08: 000000000000003e R09: 0000000000000004
[   16.874387] R10: 00000000aaaaaaaa R11: 0000000000000246 R12: 0000000000000000
[   16.874944] R13: 00000000004023e0 R14: 0000000000402470 R15: 0000000000000000
[   16.875651] Dumping ftrace buffer:
[   16.875961]    (ftrace buffer empty)
[   16.876241] Kernel Offset: disabled
[   16.876466] Rebooting in 86400 seconds..