==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: use-after-free in atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:111 [inline]
BUG: KASAN: use-after-free in __refcount_add include/linux/refcount.h:193 [inline]
BUG: KASAN: use-after-free in __refcount_inc include/linux/refcount.h:250 [inline]
BUG: KASAN: use-after-free in refcount_inc include/linux/refcount.h:267 [inline]
BUG: KASAN: use-after-free in sock_hold include/net/sock.h:701 [inline]
BUG: KASAN: use-after-free in nr_release+0x62/0x450 net/netrom/af_netrom.c:520
Write of size 4 at addr ffff88804d957080 by task syz-executor.1/10624

CPU: 0 PID: 10624 Comm: syz-executor.1 Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 print_address_description.constprop.0.cold+0x6c/0x2d6 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:111 [inline]
 __refcount_add include/linux/refcount.h:193 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 sock_hold include/net/sock.h:701 [inline]
 nr_release+0x62/0x450 net/netrom/af_netrom.c:520
 __sock_release+0xcd/0x280 net/socket.c:648
 sock_close+0x18/0x20 net/socket.c:1300
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbd4/0x2a60 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2160 kernel/signal.c:2808
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665f9
Code: Unable to access opcode bytes at RIP 0x4665cf.
RSP: 002b:00007f87a8a37188 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: fffffffffffffffc RBX: 000000000056c038 RCX: 00000000004665f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038
R13: 00007ffcbed23bff R14: 00007f87a8a37300 R15: 0000000000022000

Allocated by task 10621:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0xa1/0xd0 mm/kasan/common.c:522
 kasan_kmalloc include/linux/kasan.h:264 [inline]
 __do_kmalloc mm/slab.c:3702 [inline]
 __kmalloc+0x214/0x4d0 mm/slab.c:3711
 kmalloc include/linux/slab.h:596 [inline]
 sk_prot_alloc+0x110/0x290 net/core/sock.c:1808
 sk_alloc+0x32/0xbc0 net/core/sock.c:1861
 nr_create+0xb2/0x5f0 net/netrom/af_netrom.c:433
 __sock_create+0x353/0x790 net/socket.c:1450
 sock_create net/socket.c:1501 [inline]
 __sys_socket+0xef/0x200 net/socket.c:1543
 __do_sys_socket net/socket.c:1552 [inline]
 __se_sys_socket net/socket.c:1550 [inline]
 __x64_sys_socket+0x6f/0xb0 net/socket.c:1550
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 8485:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xd1/0x110 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:230 [inline]
 __cache_free mm/slab.c:3445 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3803
 sk_prot_free net/core/sock.c:1844 [inline]
 __sk_destruct+0x6a8/0x900 net/core/sock.c:1929
 sk_destruct+0xbd/0xe0 net/core/sock.c:1944
 __sk_free+0xef/0x3d0 net/core/sock.c:1955
 sk_free+0x78/0xa0 net/core/sock.c:1966
 sock_put include/net/sock.h:1816 [inline]
 nr_heartbeat_expiry+0x2e7/0x460 net/netrom/nr_timer.c:148
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers.part.0+0x675/0xa20 kernel/time/timer.c:1734
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xa7/0xd0 mm/kasan/generic.c:348
 kvfree_call_rcu+0x74/0x990 kernel/rcu/tree.c:3594
 drop_sysctl_table+0x3c0/0x4e0 fs/proc/proc_sysctl.c:1647
 unregister_sysctl_table fs/proc/proc_sysctl.c:1685 [inline]
 unregister_sysctl_table+0xc2/0x190 fs/proc/proc_sysctl.c:1660
 __devinet_sysctl_unregister net/ipv4/devinet.c:2595 [inline]
 devinet_sysctl_unregister net/ipv4/devinet.c:2623 [inline]
 inetdev_destroy net/ipv4/devinet.c:324 [inline]
 inetdev_event+0xcac/0x15d0 net/ipv4/devinet.c:1598
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2123
 call_netdevice_notifiers_extack net/core/dev.c:2135 [inline]
 call_netdevice_notifiers net/core/dev.c:2149 [inline]
 unregister_netdevice_many+0x951/0x1790 net/core/dev.c:11093
 ip_tunnel_delete_nets+0x39f/0x5b0 net/ipv4/ip_tunnel.c:1122
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:178
 setup_net+0x639/0xa30 net/core/net_namespace.c:356
 copy_net_ns+0x319/0x760 net/core/net_namespace.c:474
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226
 ksys_unshare+0x445/0x920 kernel/fork.c:3002
 __do_sys_unshare kernel/fork.c:3076 [inline]
 __se_sys_unshare kernel/fork.c:3074 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3074
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88804d957000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 128 bytes inside of
 2048-byte region [ffff88804d957000, ffff88804d957800)
The buggy address belongs to the page:
page:ffffea00013655c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4d957
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0001365648 ffffea0000d97b88 ffff888010840800
raw: 0000000000000000 ffff88804d957000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 9868, ts 1572748651610, free_ts 1572746180039
 prep_new_page mm/page_alloc.c:2436 [inline]
 get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4168
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5390
 __alloc_pages_node include/linux/gfp.h:570 [inline]
 kmem_getpages mm/slab.c:1377 [inline]
 cache_grow_begin+0x75/0x460 mm/slab.c:2593
 cache_alloc_refill+0x27f/0x380 mm/slab.c:2965
 ____cache_alloc mm/slab.c:3048 [inline]
 ____cache_alloc mm/slab.c:3031 [inline]
 __do_cache_alloc mm/slab.c:3275 [inline]
 slab_alloc mm/slab.c:3316 [inline]
 __do_kmalloc mm/slab.c:3700 [inline]
 __kmalloc+0x3d5/0x4d0 mm/slab.c:3711
 kmalloc include/linux/slab.h:596 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 __register_sysctl_table+0x112/0x1090 fs/proc/proc_sysctl.c:1318
 __devinet_sysctl_register+0x156/0x280 net/ipv4/devinet.c:2572
 devinet_sysctl_register net/ipv4/devinet.c:2612 [inline]
 devinet_sysctl_register+0x160/0x230 net/ipv4/devinet.c:2602
 inetdev_init+0x25d/0x550 net/ipv4/devinet.c:276
 inetdev_event+0xa87/0x15d0 net/ipv4/devinet.c:1530
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2123
 call_netdevice_notifiers_extack net/core/dev.c:2135 [inline]
 call_netdevice_notifiers net/core/dev.c:2149 [inline]
 register_netdevice+0x106b/0x1500 net/core/dev.c:10380
 __ip_tunnel_create+0x398/0x5c0 net/ipv4/ip_tunnel.c:267
 ip_tunnel_init_net+0x2e4/0x9d0 net/ipv4/ip_tunnel.c:1069
 vti_init_net+0x2a/0x370 net/ipv4/ip_vti.c:504
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1346 [inline]
 free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1397
 free_unref_page_prepare mm/page_alloc.c:3332 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3411
 __vunmap+0x783/0xb70 mm/vmalloc.c:2587
 free_work+0x58/0x70 mm/vmalloc.c:82
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
 ffff88804d956f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88804d957000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88804d957080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88804d957100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88804d957180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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