net.ipv6.conf.syz0.accept_dad = 0
net.ipv6.conf.syz0.router_solicitations = 0
executing program
syzkaller login: [   36.388380] ==================================================================
[   36.389044] BUG: KASAN: use-after-free in detach_if_pending+0x557/0x610
[   36.389670] Write of size 8 at addr ffff88003b40b740 by task syzkaller549703/3000
[   36.390369] 
[   36.390522] CPU: 0 PID: 3000 Comm: syzkaller549703 Not tainted 4.13.0-next-20170908+ #18
[   36.391384] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[   36.391977] Call Trace:
[   36.392176]  dump_stack+0x194/0x257
[   36.392440]  ? arch_local_irq_restore+0x53/0x53
[   36.392784]  ? show_regs_print_info+0x65/0x65
[   36.393114]  ? lock_timer_base+0x1a3/0x2b0
[   36.393682]  ? detach_if_pending+0x557/0x610
[   36.394156]  print_address_description+0x73/0x250
[   36.394711]  ? detach_if_pending+0x557/0x610
[   36.395189]  kasan_report+0x24e/0x340
[   36.395606]  __asan_report_store8_noabort+0x17/0x20
[   36.396240]  detach_if_pending+0x557/0x610
[   36.397361]  ? trace_raw_output_tick_stop+0x130/0x130
[   36.397747]  ? _raw_spin_lock_irqsave+0x9e/0xc0
[   36.398093]  ? lock_timer_base+0x1a3/0x2b0
[   36.398402]  ? lock_timer_base+0x1eb/0x2b0
[   36.398710]  ? __internal_add_timer+0x2d0/0x2d0
[   36.399076]  ? trace_hardirqs_on+0xd/0x10
[   36.399386]  try_to_del_timer_sync+0xa2/0x120
[   36.399710]  ? del_timer+0x130/0x130
[   36.400019]  ? del_timer_sync+0xeb/0x240
[   36.400323]  del_timer_sync+0x18a/0x240
[   36.400631]  tun_free_netdev+0x105/0x1b0
[   36.400981]  ? tun_xdp+0x410/0x410
[   36.401337]  ? cpumask_next+0x24/0x30
[   36.401689]  ? netdev_refcnt_read+0xed/0x150
[   36.402094]  ? tun_xdp+0x410/0x410
[   36.402419]  netdev_run_todo+0x870/0xca0
[   36.402791]  ? do_group_exit+0x149/0x400
[   36.403167]  ? register_netdev+0x30/0x30
[   36.403540]  ? lock_downgrade+0x990/0x990
[   36.403920]  ? trace_hardirqs_on+0xd/0x10
[   36.404316]  ? refcount_sub_and_test+0x115/0x1b0
[   36.404676]  ? refcount_inc+0x50/0x50
[   36.404959]  ? refcount_inc+0x50/0x50
[   36.405293]  ? sk_destruct+0x4c/0x80
[   36.405570]  ? __sk_free+0x5c/0x230
[   36.405841]  ? sk_free+0x2f/0x40
[   36.406088]  ? __tun_detach+0x176/0x1390
[   36.406399]  ? tun_attach+0xf90/0xf90
[   36.406683]  ? do_raw_spin_trylock+0x190/0x190
[   36.407105]  ? locks_remove_file+0x3fa/0x5a0
[   36.407511]  ? fcntl_setlk+0x10d0/0x10d0
[   36.407885]  ? __fsnotify_parent+0xb4/0x3a0
[   36.408281]  ? fsnotify+0x1af0/0x1af0
[   36.408636]  ? __tun_detach+0x1390/0x1390
[   36.409013]  ? __tun_detach+0x1390/0x1390
[   36.409388]  rtnl_unlock+0xe/0x10
[   36.409702]  tun_chr_close+0x49/0x60
[   36.410039]  __fput+0x333/0x7f0
[   36.410344]  ? fput+0x140/0x140
[   36.410644]  ? check_same_owner+0x320/0x320
[   36.411037]  ? _raw_spin_unlock_irq+0x27/0x70
[   36.411443]  ____fput+0x15/0x20
[   36.411738]  task_work_run+0x199/0x270
[   36.412090]  ? task_work_cancel+0x210/0x210
[   36.412472]  ? _raw_spin_unlock+0x22/0x30
[   36.412849]  ? switch_task_namespaces+0x87/0xc0
[   36.413271]  do_exit+0xa52/0x1b40
[   36.413583]  ? trace_hardirqs_on_caller+0x421/0x5c0
[   36.414028]  ? check_noncircular+0x20/0x20
[   36.414410]  ? __handle_mm_fault+0x587/0x39c0
[   36.414814]  ? mm_update_next_owner+0x930/0x930
[   36.415231]  ? __pmd_alloc+0x4e0/0x4e0
[   36.415591]  ? find_held_lock+0x39/0x1d0
[   36.415962]  ? lock_downgrade+0x990/0x990
[   36.416352]  ? handle_mm_fault+0x410/0x8d0
[   36.416737]  ? down_read_trylock+0xdb/0x170
[   36.417127]  ? __do_page_fault+0x2b8/0xb60
[   36.417507]  ? __handle_mm_fault+0x39c0/0x39c0
[   36.417918]  ? vmacache_find+0x61/0x270
[   36.418751]  ? up_read+0x1a/0x40
[   36.419058]  ? __do_page_fault+0x35b/0xb60
[   36.419480]  ? do_page_fault+0xee/0x720
[   36.419842]  ? __do_page_fault+0xb60/0xb60
[   36.420196]  ? putname+0xf3/0x130
[   36.420466]  do_group_exit+0x149/0x400
[   36.420831]  ? lockdep_sys_exit+0x47/0xf0
[   36.421201]  ? SyS_exit+0x30/0x30
[   36.421541]  ? trace_hardirqs_on_caller+0x421/0x5c0
[   36.421990]  ? trace_hardirqs_on_thunk+0x1a/0x1c
[   36.422426]  SyS_exit_group+0x1d/0x20
[   36.422776]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   36.423207] RIP: 0033:0x4387f9
[   36.423499] RSP: 002b:00007ffcff86ca68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[   36.424197] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004387f9
[   36.424853] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[   36.425507] RBP: 0000000000000082 R08: 000000000000003c R09: 00000000000000e7
[   36.426159] R10: ffffffffffffffc0 R11: 0000000000000246 R12: 0000000000000001
[   36.426804] R13: 00000000006cd300 R14: 00000000004022f0 R15: 0000000000000000
[   36.427456] 
[   36.427606] Allocated by task 3000:
[   36.427933]  save_stack_trace+0x16/0x20
[   36.428289]  save_stack+0x43/0xd0
[   36.428602]  kasan_kmalloc+0xad/0xe0
[   36.428933]  __kmalloc_node+0x47/0x70
[   36.429273]  kvmalloc_node+0x64/0xd0
[   36.429609]  alloc_netdev_mqs+0x16e/0xed0
[   36.429978]  __tun_chr_ioctl+0x12be/0x3d20
[   36.430355]  tun_chr_ioctl+0x2a/0x40
[   36.430687]  do_vfs_ioctl+0x1b1/0x1530
[   36.431036]  SyS_ioctl+0x8f/0xc0
[   36.431338]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   36.431760] 
[   36.431912] Freed by task 3000:
[   36.432208]  save_stack_trace+0x16/0x20
[   36.432565]  save_stack+0x43/0xd0
[   36.432875]  kasan_slab_free+0x71/0xc0
[   36.433221]  kfree+0xca/0x250
[   36.433496]  kvfree+0x36/0x60
[   36.433773]  free_netdev+0x2cf/0x360
[   36.434108]  __tun_chr_ioctl+0x2cf6/0x3d20
[   36.434487]  tun_chr_ioctl+0x2a/0x40
[   36.434821]  do_vfs_ioctl+0x1b1/0x1530
[   36.435168]  SyS_ioctl+0x8f/0xc0
[   36.435469]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   36.435909] 
[   36.436061] The buggy address belongs to the object at ffff88003b408340
[   36.436061]  which belongs to the cache kmalloc-16384 of size 16384
[   36.437154] The buggy address is located 13312 bytes inside of
[   36.437154]  16384-byte region [ffff88003b408340, ffff88003b40c340)
[   36.438236] The buggy address belongs to the page:
[   36.438677] page:ffffea0000ed0200 count:1 mapcount:0 mapping:ffff88003b408340 index:0x0 compound_mapcount: 0
[   36.440169] flags: 0x100000000008100(slab|head)
[   36.440495] raw: 0100000000008100 ffff88003b408340 0000000000000000 0000000100000001
[   36.441063] raw: ffffea0000efdc20 ffff88003e801c50 ffff88003e802200 0000000000000000
[   36.441530] page dumped because: kasan: bad access detected
[   36.441911] 
[   36.442034] Memory state around the buggy address:
[   36.442333]  ffff88003b40b600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   36.442795]  ffff88003b40b680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   36.443249] >ffff88003b40b700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   36.443730]                                            ^
[   36.444078]  ffff88003b40b780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   36.444548]  ffff88003b40b800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   36.445249] ==================================================================
[   36.445956] Disabling lock debugging due to kernel taint
[   36.446475] Kernel panic - not syncing: panic_on_warn set ...
[   36.446475] 
[   36.447186] CPU: 0 PID: 3000 Comm: syzkaller549703 Tainted: G    B           4.13.0-next-20170908+ #18
[   36.448075] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[   36.448884] Call Trace:
[   36.449133]  dump_stack+0x194/0x257
[   36.449499]  ? arch_local_irq_restore+0x53/0x53
[   36.449983]  ? vprintk_default+0x28/0x30
[   36.450372]  ? detach_if_pending+0x4c0/0x610
[   36.450807]  panic+0x1e4/0x417
[   36.451135]  ? __warn+0x1d9/0x1d9
[   36.451475]  ? detach_if_pending+0x557/0x610
[   36.451962]  kasan_end_report+0x50/0x50
[   36.452331]  kasan_report+0x137/0x340
[   36.452718]  __asan_report_store8_noabort+0x17/0x20
[   36.453160]  detach_if_pending+0x557/0x610
[   36.453594]  ? trace_raw_output_tick_stop+0x130/0x130
[   36.454081]  ? _raw_spin_lock_irqsave+0x9e/0xc0
[   36.454522]  ? lock_timer_base+0x1a3/0x2b0
[   36.454965]  ? lock_timer_base+0x1eb/0x2b0
[   36.455383]  ? __internal_add_timer+0x2d0/0x2d0
[   36.455851]  ? trace_hardirqs_on+0xd/0x10
[   36.456222]  try_to_del_timer_sync+0xa2/0x120
[   36.456556]  ? del_timer+0x130/0x130
[   36.456828]  ? del_timer_sync+0xeb/0x240
[   36.457128]  del_timer_sync+0x18a/0x240
[   36.457420]  tun_free_netdev+0x105/0x1b0
[   36.457715]  ? tun_xdp+0x410/0x410
[   36.457970]  ? cpumask_next+0x24/0x30
[   36.458251]  ? netdev_refcnt_read+0xed/0x150
[   36.458571]  ? tun_xdp+0x410/0x410
[   36.458830]  netdev_run_todo+0x870/0xca0
[   36.459118]  ? do_group_exit+0x149/0x400
[   36.459416]  ? register_netdev+0x30/0x30
[   36.459715]  ? lock_downgrade+0x990/0x990
[   36.460014]  ? trace_hardirqs_on+0xd/0x10
[   36.460386]  ? refcount_sub_and_test+0x115/0x1b0
[   36.461255]  ? refcount_inc+0x50/0x50
[   36.461587]  ? refcount_inc+0x50/0x50
[   36.461852]  ? sk_destruct+0x4c/0x80
[   36.462107]  ? __sk_free+0x5c/0x230
[   36.462358]  ? sk_free+0x2f/0x40
[   36.462592]  ? __tun_detach+0x176/0x1390
[   36.462888]  ? tun_attach+0xf90/0xf90
[   36.463168]  ? do_raw_spin_trylock+0x190/0x190
[   36.463474]  ? locks_remove_file+0x3fa/0x5a0
[   36.463793]  ? fcntl_setlk+0x10d0/0x10d0
[   36.464187]  ? __fsnotify_parent+0xb4/0x3a0
[   36.464600]  ? fsnotify+0x1af0/0x1af0
[   36.464967]  ? __tun_detach+0x1390/0x1390
[   36.465350]  ? __tun_detach+0x1390/0x1390
[   36.465679]  rtnl_unlock+0xe/0x10
[   36.465913]  tun_chr_close+0x49/0x60
[   36.466164]  __fput+0x333/0x7f0
[   36.466416]  ? fput+0x140/0x140
[   36.466637]  ? check_same_owner+0x320/0x320
[   36.466944]  ? _raw_spin_unlock_irq+0x27/0x70
[   36.467268]  ____fput+0x15/0x20
[   36.467493]  task_work_run+0x199/0x270
[   36.467753]  ? task_work_cancel+0x210/0x210
[   36.468043]  ? _raw_spin_unlock+0x22/0x30
[   36.468323]  ? switch_task_namespaces+0x87/0xc0
[   36.468642]  do_exit+0xa52/0x1b40
[   36.468876]  ? trace_hardirqs_on_caller+0x421/0x5c0
[   36.469217]  ? check_noncircular+0x20/0x20
[   36.469504]  ? __handle_mm_fault+0x587/0x39c0
[   36.469810]  ? mm_update_next_owner+0x930/0x930
[   36.470128]  ? __pmd_alloc+0x4e0/0x4e0
[   36.470396]  ? find_held_lock+0x39/0x1d0
[   36.470676]  ? lock_downgrade+0x990/0x990
[   36.470975]  ? handle_mm_fault+0x410/0x8d0
[   36.471265]  ? down_read_trylock+0xdb/0x170
[   36.471557]  ? __do_page_fault+0x2b8/0xb60
[   36.471851]  ? __handle_mm_fault+0x39c0/0x39c0
[   36.472155]  ? vmacache_find+0x61/0x270
[   36.472425]  ? up_read+0x1a/0x40
[   36.472654]  ? __do_page_fault+0x35b/0xb60
[   36.472944]  ? do_page_fault+0xee/0x720
[   36.473205]  ? __do_page_fault+0xb60/0xb60
[   36.473486]  ? putname+0xf3/0x130
[   36.473723]  do_group_exit+0x149/0x400
[   36.473987]  ? lockdep_sys_exit+0x47/0xf0
[   36.474264]  ? SyS_exit+0x30/0x30
[   36.474496]  ? trace_hardirqs_on_caller+0x421/0x5c0
[   36.474835]  ? trace_hardirqs_on_thunk+0x1a/0x1c
[   36.475153]  SyS_exit_group+0x1d/0x20
[   36.475483]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   36.475807] RIP: 0033:0x4387f9
[   36.476027] RSP: 002b:00007ffcff86ca68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[   36.476545] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004387f9
[   36.477034] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[   36.477542] RBP: 0000000000000082 R08: 000000000000003c R09: 00000000000000e7
[   36.478032] R10: ffffffffffffffc0 R11: 0000000000000246 R12: 0000000000000001
[   36.478519] R13: 00000000006cd300 R14: 00000000004022f0 R15: 0000000000000000