==================================================================
BUG: KASAN: use-after-free in strlcpy include/linux/string.h:355 [inline]
BUG: KASAN: use-after-free in kernfs_path_from_node_locked+0x9b3/0xc80 fs/kernfs/dir.c:138
Write of size 1 at addr ffff88801168e000 by task syz-executor.5/31448

CPU: 0 PID: 31448 Comm: syz-executor.5 Not tainted 5.10.0-rc5-next-20201126-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230
 __kasan_report mm/kasan/report.c:396 [inline]
 kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413
 check_memory_region_inline mm/kasan/generic.c:180 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:186
 memcpy+0x39/0x60 mm/kasan/shadow.c:66
 strlcpy include/linux/string.h:355 [inline]
 kernfs_path_from_node_locked+0x9b3/0xc80 fs/kernfs/dir.c:138
 kernfs_path_from_node+0x3a/0x60 fs/kernfs/dir.c:217
 kernfs_path include/linux/kernfs.h:542 [inline]
 cgroup_path include/linux/cgroup.h:661 [inline]
 get_mm_memcg_path+0xb2/0xf0 mm/mmap_lock.c:130
 __mmap_lock_do_trace_released+0x25/0x2d0 mm/mmap_lock.c:185
 __mmap_lock_trace_released include/linux/mmap_lock.h:42 [inline]
 mmap_read_unlock include/linux/mmap_lock.h:144 [inline]
 maybe_unlock_mmap_for_io mm/internal.h:425 [inline]
 fault_dirty_shared_page+0x37a/0x400 mm/memory.c:2770
 do_shared_fault mm/memory.c:4097 [inline]
 do_fault mm/memory.c:4149 [inline]
 handle_pte_fault mm/memory.c:4385 [inline]
 __handle_mm_fault mm/memory.c:4520 [inline]
 handle_mm_fault+0x3127/0x55d0 mm/memory.c:4618
 do_user_addr_fault+0x570/0xc50 arch/x86/mm/fault.c:1398
 handle_page_fault arch/x86/mm/fault.c:1455 [inline]
 exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1511
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:580
RIP: 0033:0x403907
Code: 00 00 00 48 83 ec 08 48 8b 15 95 1a 2a 01 48 8b 05 86 1a 2a 01 48 39 d0 48 8d 8a 00 00 00 01 72 17 48 39 c8 73 12 48 8d 50 04 <89> 38 48 89 15 68 1a 2a 01 48 83 c4 08 c3 48 89 c6 bf 78 28 4d 00
RSP: 002b:00007ffc13c899a0 EFLAGS: 00010287
RAX: 0000001b31520000 RBX: 0000000000000000 RCX: 0000001b32520000
RDX: 0000001b31520004 RSI: 00007ffc13c89760 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000004
R10: 0000000000000075 R11: 0000000000000000 R12: 0000000000000000
R13: 00007ffc13c89b90 R14: 0000000000000000 R15: 00007ffc13c89ba0

Allocated by task 31447:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:39
 kasan_set_track mm/kasan/common.c:47 [inline]
 set_alloc_info mm/kasan/common.c:405 [inline]
 ____kasan_kmalloc mm/kasan/common.c:436 [inline]
 ____kasan_kmalloc.constprop.0+0xa0/0xd0 mm/kasan/common.c:408
 kmalloc include/linux/slab.h:552 [inline]
 trace_mmap_lock_reg+0x196/0x550 mm/mmap_lock.c:58
 tracepoint_add_func+0x304/0x990 kernel/tracepoint.c:257
 tracepoint_probe_register_prio kernel/tracepoint.c:342 [inline]
 tracepoint_probe_register+0x9c/0xe0 kernel/tracepoint.c:362
 trace_event_reg+0x28f/0x350 kernel/trace/trace_events.c:305
 perf_trace_event_reg kernel/trace/trace_event_perf.c:129 [inline]
 perf_trace_event_init+0x549/0xa20 kernel/trace/trace_event_perf.c:204
 perf_trace_init+0x176/0x240 kernel/trace/trace_event_perf.c:228
 perf_tp_event_init+0xa2/0x120 kernel/events/core.c:9590
 perf_try_init_event+0x12a/0x560 kernel/events/core.c:11058
 perf_init_event kernel/events/core.c:11110 [inline]
 perf_event_alloc.part.0+0xe04/0x38b0 kernel/events/core.c:11388
 perf_event_alloc kernel/events/core.c:11767 [inline]
 __do_sys_perf_event_open+0x72c/0x2cb0 kernel/events/core.c:11883
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 31442:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:39
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:47
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:358
 ____kasan_slab_free.part.0+0xe1/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:187 [inline]
 slab_free_hook mm/slub.c:1548 [inline]
 slab_free_freelist_hook+0x82/0x1d0 mm/slub.c:1586
 slab_free mm/slub.c:3157 [inline]
 kfree+0xe5/0x5c0 mm/slub.c:4156
 trace_mmap_lock_unreg+0xba/0x160 mm/mmap_lock.c:94
 tracepoint_remove_func kernel/tracepoint.c:306 [inline]
 tracepoint_probe_unregister+0x5b6/0x890 kernel/tracepoint.c:382
 trace_event_reg+0x181/0x350 kernel/trace/trace_events.c:309
 perf_trace_event_unreg.isra.0+0xac/0x250 kernel/trace/trace_event_perf.c:162
 perf_trace_destroy+0xb5/0xf0 kernel/trace/trace_event_perf.c:243
 _free_event+0x2ee/0x1300 kernel/events/core.c:4840
 put_event kernel/events/core.c:4934 [inline]
 perf_event_release_kernel+0xa24/0xe00 kernel/events/core.c:5049
 perf_release+0x33/0x40 kernel/events/core.c:5059
 __fput+0x283/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x190 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x1f0/0x200 kernel/entry/common.c:198
 syscall_exit_to_user_mode+0x36/0x260 kernel/entry/common.c:275
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Last call_rcu():
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:39
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:346
 kvfree_call_rcu+0x74/0x930 kernel/rcu/tree.c:3533
 drop_sysctl_table+0x3c0/0x4e0 fs/proc/proc_sysctl.c:1643
 unregister_sysctl_table fs/proc/proc_sysctl.c:1681 [inline]
 unregister_sysctl_table+0xbd/0x190 fs/proc/proc_sysctl.c:1656
 neigh_sysctl_unregister+0x5b/0x80 net/core/neighbour.c:3716
 addrconf_ifdown.isra.0+0xf8d/0x1590 net/ipv6/addrconf.c:3846
 addrconf_notify+0x55c/0x23f0 net/ipv6/addrconf.c:3628
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2035
 call_netdevice_notifiers_extack net/core/dev.c:2047 [inline]
 call_netdevice_notifiers net/core/dev.c:2061 [inline]
 rollback_registered_many+0x92e/0x14c0 net/core/dev.c:9423
 unregister_netdevice_many.part.0+0x1a/0x2f0 net/core/dev.c:10642
 unregister_netdevice_many+0x36/0x50 net/core/dev.c:10641
 ip_tunnel_delete_nets+0x3eb/0x5b0 net/ipv4/ip_tunnel.c:1116
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:190
 setup_net+0x508/0x850 net/core/net_namespace.c:365
 copy_net_ns+0x31e/0x760 net/core/net_namespace.c:483
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 copy_namespaces+0x385/0x470 kernel/nsproxy.c:179
 copy_process+0x2a87/0x6fb0 kernel/fork.c:2100
 kernel_clone+0xe7/0xab0 kernel/fork.c:2462
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2579
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Second to last call_rcu():
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:39
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:346
 __call_rcu kernel/rcu/tree.c:2981 [inline]
 call_rcu+0xbb/0x760 kernel/rcu/tree.c:3056
 sctp_transport_destroy net/sctp/transport.c:167 [inline]
 sctp_transport_put+0x11d/0x180 net/sctp/transport.c:326
 sctp_association_free+0x4d4/0x7d0 net/sctp/associola.c:381
 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:930 [inline]
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1318 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
 sctp_do_sm+0x38b8/0x5120 net/sctp/sm_sideeffect.c:1156
 sctp_assoc_bh_rcv+0x386/0x6c0 net/sctp/associola.c:1048
 sctp_inq_push+0x1da/0x270 net/sctp/inqueue.c:80
 sctp_backlog_rcv+0x19e/0x5c0 net/sctp/input.c:344
 sk_backlog_rcv include/net/sock.h:1010 [inline]
 __release_sock+0x134/0x3a0 net/core/sock.c:2523
 release_sock+0x54/0x1b0 net/core/sock.c:3053
 sctp_wait_for_connect+0x1cb/0x5d0 net/sctp/socket.c:9177
 __sctp_connect+0x9a9/0xc30 net/sctp/socket.c:1230
 sctp_connect net/sctp/socket.c:4730 [inline]
 sctp_inet_connect+0x15e/0x200 net/sctp/socket.c:4745
 __sys_connect_file+0x155/0x1a0 net/socket.c:1830
 __sys_connect+0x161/0x190 net/socket.c:1847
 __do_sys_connect net/socket.c:1857 [inline]
 __se_sys_connect net/socket.c:1854 [inline]
 __x64_sys_connect+0x6f/0xb0 net/socket.c:1854
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88801168e000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 0 bytes inside of
 1024-byte region [ffff88801168e000, ffff88801168e400)
The buggy address belongs to the page:
page:00000000f7675f8c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1168c
head:00000000f7675f8c order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 0000000000000000 0000000100000001 ffff888010041140
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88801168df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801168df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801168e000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88801168e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801168e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================