Buffer I/O error on dev loop0, logical block 0, async page read
==================================================================
BUG: KASAN: use-after-free in ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400 at addr ffff8801a7f53a80
Read of size 8 by task syz-executor6/26178
CPU: 0 PID: 26178 Comm: syz-executor6 Not tainted 4.9.65-g8ae26d1 #98
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d80974f0 ffffffff81d90469 ffff8801da001140 ffff8801a7f53a80
 ffff8801a7f53e80 ffffed0034fea750 ffff8801a7f53a80 ffff8801d8097518
 ffffffff8153a3fc ffffed0034fea750 ffff8801da001140 0000000000000000
Call Trace:
 [<ffffffff81d90469>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90469>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8153a3fc>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:160
 [<ffffffff8153a6bc>] print_address_description mm/kasan/report.c:198 [inline]
 [<ffffffff8153a6bc>] kasan_report_error mm/kasan/report.c:287 [inline]
 [<ffffffff8153a6bc>] kasan_report.part.1+0x21c/0x500 mm/kasan/report.c:309
 [<ffffffff8153aa59>] kasan_report mm/kasan/report.c:330 [inline]
 [<ffffffff8153aa59>] __asan_report_load8_noabort+0x29/0x30 mm/kasan/report.c:330
 [<ffffffff83457091>] ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400
 [<ffffffff82f55da5>] dst_ifdown+0x75/0x230 net/core/dst.c:440
 [<ffffffff82f569f1>] dst_dev_event+0xb1/0x2e0 net/core/dst.c:467
 [<ffffffff8119ce90>] notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 [<ffffffff8119d01d>] __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 [<ffffffff8119d01d>] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 [<ffffffff82f20d01>] call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 [<ffffffff82f21994>] call_netdevice_notifiers net/core/dev.c:1662 [inline]
 [<ffffffff82f21994>] dev_close_many+0x254/0x370 net/core/dev.c:1455
 [<ffffffff82f26ffa>] rollback_registered_many+0x27a/0x960 net/core/dev.c:6783
 [<ffffffff82f27761>] rollback_registered+0x81/0xb0 net/core/dev.c:6846
 [<ffffffff82f2a551>] unregister_netdevice_queue+0x81/0x140 net/core/dev.c:7833
 [<ffffffff827085fc>] unregister_netdevice include/linux/netdevice.h:2458 [inline]
 [<ffffffff827085fc>] __tun_detach+0xa2c/0xc20 drivers/net/tun.c:567
 [<ffffffff82708834>] tun_detach drivers/net/tun.c:578 [inline]
 [<ffffffff82708834>] tun_chr_close+0x44/0x60 drivers/net/tun.c:2379
 [<ffffffff8157182c>] __fput+0x28c/0x6e0 fs/file_table.c:208
 [<ffffffff81571d05>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff81193675>] task_work_run+0x115/0x190 kernel/task_work.c:116
 [<ffffffff8113a507>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff8113a507>] do_exit+0x7e7/0x2a40 kernel/exit.c:833
 [<ffffffff81140c18>] do_group_exit+0x108/0x320 kernel/exit.c:937
 [<ffffffff81163a44>] get_signal+0x4d4/0x14e0 kernel/signal.c:2315
 [<ffffffff81052c87>] do_signal+0x87/0x1a00 arch/x86/kernel/signal.c:807
 [<ffffffff81003a31>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:156
 [<ffffffff81006340>] prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline]
 [<ffffffff81006340>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
 [<ffffffff838a97e6>] entry_SYSCALL_64_fastpath+0xc4/0xc6
Object at ffff8801a7f53a80, in cache kmalloc-1024 size: 1024
Allocated:
PID = 3350
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:598
 kmem_cache_alloc_trace+0xfb/0x2a0 mm/slub.c:2742
 kmalloc include/linux/slab.h:490 [inline]
 kzalloc include/linux/slab.h:636 [inline]
 ipv6_add_dev+0xbb/0x1000 net/ipv6/addrconf.c:371
 addrconf_notify+0xa5e/0x2190 net/ipv6/addrconf.c:3356
 notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 call_netdevice_notifiers net/core/dev.c:1662 [inline]
 register_netdevice+0xb92/0xea0 net/core/dev.c:7294
 register_netdev+0x1a/0x30 net/core/dev.c:7377
 loopback_net_init+0x76/0x160 drivers/net/loopback.c:202
 ops_init+0xa9/0x3a0 net/core/net_namespace.c:111
 setup_net+0x1b2/0x3e0 net/core/net_namespace.c:291
 copy_net_ns+0x189/0x280 net/core/net_namespace.c:389
 create_new_namespaces+0x37f/0x730 kernel/nsproxy.c:106
 copy_namespaces+0x291/0x320 kernel/nsproxy.c:164
 copy_process.part.51+0x1c99/0x5d40 kernel/fork.c:1667
 copy_process kernel/fork.c:1491 [inline]
 _do_fork+0x1c0/0xd70 kernel/fork.c:1949
 SYSC_clone kernel/fork.c:2059 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2053
 do_syscall_64+0x197/0x490 arch/x86/entry/common.c:280
 return_from_SYSCALL_64+0x0/0x7a
Freed:
PID = 0
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:571
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kfree+0xf0/0x2f0 mm/slub.c:3878
 in6_dev_finish_destroy_rcu+0x9d/0xc0 net/ipv6/addrconf_core.c:150
 __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 rcu_process_callbacks+0x871/0x12c0 kernel/rcu/tree.c:3037
 __do_softirq+0x206/0x951 kernel/softirq.c:284
Memory state around the buggy address:
 ffff8801a7f53980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801a7f53a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801a7f53b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
==================================================================
BUG: KASAN: use-after-free in ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400 at addr ffff8801a7f53a80
Read of size 8 by task syz-executor6/26178
CPU: 0 PID: 26178 Comm: syz-executor6 Tainted: G    B           4.9.65-g8ae26d1 #98
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d80974f0 ffffffff81d90469 ffff8801da001140 ffff8801a7f53a80
 ffff8801a7f53e80 ffffed0034fea750 ffff8801a7f53a80 ffff8801d8097518
 ffffffff8153a3fc ffffed0034fea750 ffff8801da001140 0000000000000000
Call Trace:
 [<ffffffff81d90469>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90469>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8153a3fc>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:160
 [<ffffffff8153a6bc>] print_address_description mm/kasan/report.c:198 [inline]
 [<ffffffff8153a6bc>] kasan_report_error mm/kasan/report.c:287 [inline]
 [<ffffffff8153a6bc>] kasan_report.part.1+0x21c/0x500 mm/kasan/report.c:309
 [<ffffffff8153aa59>] kasan_report mm/kasan/report.c:330 [inline]
 [<ffffffff8153aa59>] __asan_report_load8_noabort+0x29/0x30 mm/kasan/report.c:330
 [<ffffffff83457091>] ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400
 [<ffffffff82f55da5>] dst_ifdown+0x75/0x230 net/core/dst.c:440
 [<ffffffff82f569f1>] dst_dev_event+0xb1/0x2e0 net/core/dst.c:467
 [<ffffffff8119ce90>] notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 [<ffffffff8119d01d>] __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 [<ffffffff8119d01d>] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 [<ffffffff82f20d01>] call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 [<ffffffff82f21994>] call_netdevice_notifiers net/core/dev.c:1662 [inline]
 [<ffffffff82f21994>] dev_close_many+0x254/0x370 net/core/dev.c:1455
 [<ffffffff82f26ffa>] rollback_registered_many+0x27a/0x960 net/core/dev.c:6783
 [<ffffffff82f27761>] rollback_registered+0x81/0xb0 net/core/dev.c:6846
 [<ffffffff82f2a551>] unregister_netdevice_queue+0x81/0x140 net/core/dev.c:7833
 [<ffffffff827085fc>] unregister_netdevice include/linux/netdevice.h:2458 [inline]
 [<ffffffff827085fc>] __tun_detach+0xa2c/0xc20 drivers/net/tun.c:567
 [<ffffffff82708834>] tun_detach drivers/net/tun.c:578 [inline]
 [<ffffffff82708834>] tun_chr_close+0x44/0x60 drivers/net/tun.c:2379
 [<ffffffff8157182c>] __fput+0x28c/0x6e0 fs/file_table.c:208
 [<ffffffff81571d05>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff81193675>] task_work_run+0x115/0x190 kernel/task_work.c:116
 [<ffffffff8113a507>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff8113a507>] do_exit+0x7e7/0x2a40 kernel/exit.c:833
 [<ffffffff81140c18>] do_group_exit+0x108/0x320 kernel/exit.c:937
 [<ffffffff81163a44>] get_signal+0x4d4/0x14e0 kernel/signal.c:2315
 [<ffffffff81052c87>] do_signal+0x87/0x1a00 arch/x86/kernel/signal.c:807
 [<ffffffff81003a31>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:156
 [<ffffffff81006340>] prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline]
 [<ffffffff81006340>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
 [<ffffffff838a97e6>] entry_SYSCALL_64_fastpath+0xc4/0xc6
Object at ffff8801a7f53a80, in cache kmalloc-1024 size: 1024
Allocated:
PID = 3350
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:598
 kmem_cache_alloc_trace+0xfb/0x2a0 mm/slub.c:2742
 kmalloc include/linux/slab.h:490 [inline]
 kzalloc include/linux/slab.h:636 [inline]
 ipv6_add_dev+0xbb/0x1000 net/ipv6/addrconf.c:371
 addrconf_notify+0xa5e/0x2190 net/ipv6/addrconf.c:3356
 notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 call_netdevice_notifiers net/core/dev.c:1662 [inline]
 register_netdevice+0xb92/0xea0 net/core/dev.c:7294
 register_netdev+0x1a/0x30 net/core/dev.c:7377
 loopback_net_init+0x76/0x160 drivers/net/loopback.c:202
 ops_init+0xa9/0x3a0 net/core/net_namespace.c:111
 setup_net+0x1b2/0x3e0 net/core/net_namespace.c:291
 copy_net_ns+0x189/0x280 net/core/net_namespace.c:389
 create_new_namespaces+0x37f/0x730 kernel/nsproxy.c:106
 copy_namespaces+0x291/0x320 kernel/nsproxy.c:164
 copy_process.part.51+0x1c99/0x5d40 kernel/fork.c:1667
 copy_process kernel/fork.c:1491 [inline]
 _do_fork+0x1c0/0xd70 kernel/fork.c:1949
 SYSC_clone kernel/fork.c:2059 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2053
 do_syscall_64+0x197/0x490 arch/x86/entry/common.c:280
 return_from_SYSCALL_64+0x0/0x7a
Freed:
PID = 0
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:571
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kfree+0xf0/0x2f0 mm/slub.c:3878
 in6_dev_finish_destroy_rcu+0x9d/0xc0 net/ipv6/addrconf_core.c:150
 __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 rcu_process_callbacks+0x871/0x12c0 kernel/rcu/tree.c:3037
 __do_softirq+0x206/0x951 kernel/softirq.c:284
Memory state around the buggy address:
 ffff8801a7f53980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801a7f53a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801a7f53b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
==================================================================
BUG: KASAN: use-after-free in ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400 at addr ffff8801a7f53a80
Read of size 8 by task syz-executor6/26178
CPU: 1 PID: 26178 Comm: syz-executor6 Tainted: G    B           4.9.65-g8ae26d1 #98
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8097698 ffffffff81d90469 ffff8801da001140 ffff8801a7f53a80
 ffff8801a7f53e80 ffffed0034fea750 ffff8801a7f53a80 ffff8801d80976c0
 ffffffff8153a3fc ffffed0034fea750 ffff8801da001140 0000000000000000
Call Trace:
 [<ffffffff81d90469>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90469>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8153a3fc>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:160
 [<ffffffff8153a6bc>] print_address_description mm/kasan/report.c:198 [inline]
 [<ffffffff8153a6bc>] kasan_report_error mm/kasan/report.c:287 [inline]
 [<ffffffff8153a6bc>] kasan_report.part.1+0x21c/0x500 mm/kasan/report.c:309
 [<ffffffff8153aa59>] kasan_report mm/kasan/report.c:330 [inline]
 [<ffffffff8153aa59>] __asan_report_load8_noabort+0x29/0x30 mm/kasan/report.c:330
 [<ffffffff83457091>] ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400
 [<ffffffff82f55da5>] dst_ifdown+0x75/0x230 net/core/dst.c:440
 [<ffffffff82f569f1>] dst_dev_event+0xb1/0x2e0 net/core/dst.c:467
 [<ffffffff8119ce90>] notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 [<ffffffff8119d01d>] __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 [<ffffffff8119d01d>] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 [<ffffffff82f20d01>] call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 [<ffffffff82f482ba>] call_netdevice_notifiers net/core/dev.c:1662 [inline]
 [<ffffffff82f482ba>] netdev_run_todo+0x17a/0x6b0 net/core/dev.c:7499
 [<ffffffff82f6d44e>] rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:104
 [<ffffffff82708839>] tun_detach drivers/net/tun.c:579 [inline]
 [<ffffffff82708839>] tun_chr_close+0x49/0x60 drivers/net/tun.c:2379
 [<ffffffff8157182c>] __fput+0x28c/0x6e0 fs/file_table.c:208
 [<ffffffff81571d05>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff81193675>] task_work_run+0x115/0x190 kernel/task_work.c:116
 [<ffffffff8113a507>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff8113a507>] do_exit+0x7e7/0x2a40 kernel/exit.c:833
 [<ffffffff81140c18>] do_group_exit+0x108/0x320 kernel/exit.c:937
 [<ffffffff81163a44>] get_signal+0x4d4/0x14e0 kernel/signal.c:2315
 [<ffffffff81052c87>] do_signal+0x87/0x1a00 arch/x86/kernel/signal.c:807
 [<ffffffff81003a31>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:156
 [<ffffffff81006340>] prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline]
 [<ffffffff81006340>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
 [<ffffffff838a97e6>] entry_SYSCALL_64_fastpath+0xc4/0xc6
Object at ffff8801a7f53a80, in cache kmalloc-1024 size: 1024
Allocated:
PID = 3350
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:598
 kmem_cache_alloc_trace+0xfb/0x2a0 mm/slub.c:2742
 kmalloc include/linux/slab.h:490 [inline]
 kzalloc include/linux/slab.h:636 [inline]
 ipv6_add_dev+0xbb/0x1000 net/ipv6/addrconf.c:371
 addrconf_notify+0xa5e/0x2190 net/ipv6/addrconf.c:3356
 notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 call_netdevice_notifiers net/core/dev.c:1662 [inline]
 register_netdevice+0xb92/0xea0 net/core/dev.c:7294
 register_netdev+0x1a/0x30 net/core/dev.c:7377
 loopback_net_init+0x76/0x160 drivers/net/loopback.c:202
 ops_init+0xa9/0x3a0 net/core/net_namespace.c:111
 setup_net+0x1b2/0x3e0 net/core/net_namespace.c:291
 copy_net_ns+0x189/0x280 net/core/net_namespace.c:389
 create_new_namespaces+0x37f/0x730 kernel/nsproxy.c:106
 copy_namespaces+0x291/0x320 kernel/nsproxy.c:164
 copy_process.part.51+0x1c99/0x5d40 kernel/fork.c:1667
 copy_process kernel/fork.c:1491 [inline]
 _do_fork+0x1c0/0xd70 kernel/fork.c:1949
 SYSC_clone kernel/fork.c:2059 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2053
 do_syscall_64+0x197/0x490 arch/x86/entry/common.c:280
 return_from_SYSCALL_64+0x0/0x7a
Freed:
PID = 0
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:571
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kfree+0xf0/0x2f0 mm/slub.c:3878
 in6_dev_finish_destroy_rcu+0x9d/0xc0 net/ipv6/addrconf_core.c:150
 __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 rcu_process_callbacks+0x871/0x12c0 kernel/rcu/tree.c:3037
 __do_softirq+0x206/0x951 kernel/softirq.c:284
Memory state around the buggy address:
 ffff8801a7f53980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801a7f53a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801a7f53b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
==================================================================
BUG: KASAN: use-after-free in ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400 at addr ffff8801a7f53a80
Read of size 8 by task syz-executor6/26178
CPU: 0 PID: 26178 Comm: syz-executor6 Tainted: G    B           4.9.65-g8ae26d1 #98
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8097698 ffffffff81d90469 ffff8801da001140 ffff8801a7f53a80
 ffff8801a7f53e80 ffffed0034fea750 ffff8801a7f53a80 ffff8801d80976c0
 ffffffff8153a3fc ffffed0034fea750 ffff8801da001140 0000000000000000
Call Trace:
 [<ffffffff81d90469>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90469>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8153a3fc>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:160
 [<ffffffff8153a6bc>] print_address_description mm/kasan/report.c:198 [inline]
 [<ffffffff8153a6bc>] kasan_report_error mm/kasan/report.c:287 [inline]
 [<ffffffff8153a6bc>] kasan_report.part.1+0x21c/0x500 mm/kasan/report.c:309
 [<ffffffff8153aa59>] kasan_report mm/kasan/report.c:330 [inline]
 [<ffffffff8153aa59>] __asan_report_load8_noabort+0x29/0x30 mm/kasan/report.c:330
 [<ffffffff83457091>] ip6_dst_ifdown+0x2f1/0x320 net/ipv6/route.c:400
 [<ffffffff82f55da5>] dst_ifdown+0x75/0x230 net/core/dst.c:440
 [<ffffffff82f569f1>] dst_dev_event+0xb1/0x2e0 net/core/dst.c:467
 [<ffffffff8119ce90>] notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 [<ffffffff8119d01d>] __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 [<ffffffff8119d01d>] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 [<ffffffff82f20d01>] call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 [<ffffffff82f482ba>] call_netdevice_notifiers net/core/dev.c:1662 [inline]
 [<ffffffff82f482ba>] netdev_run_todo+0x17a/0x6b0 net/core/dev.c:7499
 [<ffffffff82f6d44e>] rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:104
 [<ffffffff82708839>] tun_detach drivers/net/tun.c:579 [inline]
 [<ffffffff82708839>] tun_chr_close+0x49/0x60 drivers/net/tun.c:2379
 [<ffffffff8157182c>] __fput+0x28c/0x6e0 fs/file_table.c:208
 [<ffffffff81571d05>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff81193675>] task_work_run+0x115/0x190 kernel/task_work.c:116
 [<ffffffff8113a507>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff8113a507>] do_exit+0x7e7/0x2a40 kernel/exit.c:833
 [<ffffffff81140c18>] do_group_exit+0x108/0x320 kernel/exit.c:937
 [<ffffffff81163a44>] get_signal+0x4d4/0x14e0 kernel/signal.c:2315
 [<ffffffff81052c87>] do_signal+0x87/0x1a00 arch/x86/kernel/signal.c:807
 [<ffffffff81003a31>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:156
 [<ffffffff81006340>] prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline]
 [<ffffffff81006340>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
 [<ffffffff838a97e6>] entry_SYSCALL_64_fastpath+0xc4/0xc6
Object at ffff8801a7f53a80, in cache kmalloc-1024 size: 1024
Allocated:
PID = 3350
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:598
 kmem_cache_alloc_trace+0xfb/0x2a0 mm/slub.c:2742
 kmalloc include/linux/slab.h:490 [inline]
 kzalloc include/linux/slab.h:636 [inline]
 ipv6_add_dev+0xbb/0x1000 net/ipv6/addrconf.c:371
 addrconf_notify+0xa5e/0x2190 net/ipv6/addrconf.c:3356
 notifier_call_chain+0x90/0x1a0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
 call_netdevice_notifiers net/core/dev.c:1662 [inline]
 register_netdevice+0xb92/0xea0 net/core/dev.c:7294
 register_netdev+0x1a/0x30 net/core/dev.c:7377
 loopback_net_init+0x76/0x160 drivers/net/loopback.c:202
 ops_init+0xa9/0x3a0 net/core/net_namespace.c:111
 setup_net+0x1b2/0x3e0 net/core/net_namespace.c:291
 copy_net_ns+0x189/0x280 net/core/net_namespace.c:389
 create_new_namespaces+0x37f/0x730 kernel/nsproxy.c:106
 copy_namespaces+0x291/0x320 kernel/nsproxy.c:164
 copy_process.part.51+0x1c99/0x5d40 kernel/fork.c:1667
 copy_process kernel/fork.c:1491 [inline]
 _do_fork+0x1c0/0xd70 kernel/fork.c:1949
 SYSC_clone kernel/fork.c:2059 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2053
 do_syscall_64+0x197/0x490 arch/x86/entry/common.c:280
 return_from_SYSCALL_64+0x0/0x7a
Freed:
PID = 0
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:495
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:571
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kfree+0xf0/0x2f0 mm/slub.c:3878
 in6_dev_finish_destroy_rcu+0x9d/0xc0 net/ipv6/addrconf_core.c:150
 __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 rcu_process_callbacks+0x871/0x12c0 kernel/rcu/tree.c:3037
 __do_softirq+0x206/0x951 kernel/softirq.c:284
Memory state around the buggy address:
 ffff8801a7f53980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801a7f53a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801a7f53b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a7f53b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
unregister_netdevice: waiting for lo to become free. Usage count = 2