bond2 (unregistering): Released all slaves
bond1 (unregistering): Releasing backup interface veth521
device veth521 left promiscuous mode
bond1 (unregistering): Released all slaves
==================================================================
BUG: KASAN: use-after-free in qfq_reset_qdisc+0x239/0x2b0 net/sched/sch_qfq.c:1463
Read of size 8 at addr ffff8880a71e3a08 by task kworker/u4:2/27

CPU: 0 PID: 27 Comm: kworker/u4:2 Not tainted 4.14.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2b9 mm/kasan/report.c:393
 qfq_reset_qdisc+0x239/0x2b0 net/sched/sch_qfq.c:1463
 qdisc_destroy+0x104/0x310 net/sched/sch_generic.c:723
 dev_shutdown+0x27d/0x42d net/sched/sch_generic.c:1000
 rollback_registered_many+0x684/0xa70 net/core/dev.c:7200
 unregister_netdevice_many.part.0+0x16/0x1d0 net/core/dev.c:8281
 unregister_netdevice_many net/core/dev.c:8280 [inline]
 default_device_exit_batch+0x2dd/0x380 net/core/dev.c:8742
 ops_exit_list.isra.0+0xef/0x140 net/core/net_namespace.c:145
 cleanup_net+0x3bb/0x820 net/core/net_namespace.c:484
 process_one_work+0x7c0/0x14c0 kernel/workqueue.c:2116
 worker_thread+0x5d7/0x1080 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 6978:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x14d/0x3f0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 minix_fill_super+0x52/0x1900 fs/minix/inode.c:169
 mount_bdev+0x2b3/0x360 fs/super.c:1134
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x3c0 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0x3c9/0x25e0 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 6335:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 generic_shutdown_super+0x144/0x370 fs/super.c:446
 kill_block_super+0x95/0xe0 fs/super.c:1161
 deactivate_locked_super+0x6c/0xd0 fs/super.c:319
 deactivate_super fs/super.c:350 [inline]
 deactivate_super+0x7f/0xa0 fs/super.c:346
 cleanup_mnt+0xad/0x140 fs/namespace.c:1183
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880a71e39c0
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 72 bytes inside of
 128-byte region [ffff8880a71e39c0, ffff8880a71e3a40)
The buggy address belongs to the page:
page:ffffea00029c78c0 count:1 mapcount:0 mapping:ffff8880a71e3000 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a71e3000 0000000000000000 0000000100000015
raw: ffffea00026e0c60 ffffea00029cd2e0 ffff8880aa800640 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a71e3900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880a71e3980: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880a71e3a00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                      ^
 ffff8880a71e3a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
 ffff8880a71e3b00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================