==================================================================
BUG: KASAN: use-after-free in notifier_call_chain kernel/notifier.c:72 [inline]
BUG: KASAN: use-after-free in raw_notifier_call_chain+0x3e/0x170 kernel/notifier.c:392
Read of size 8 at addr ffff8880266f8268 by task syz-executor.1/3619

CPU: 0 PID: 3619 Comm: syz-executor.1 Not tainted 5.18.0-rc4-syzkaller-00291-g8013d1d3d2e3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description+0x65/0x4b0 mm/kasan/report.c:313
 print_report+0xf4/0x210 mm/kasan/report.c:429
 kasan_report+0xfb/0x130 mm/kasan/report.c:491
 notifier_call_chain kernel/notifier.c:72 [inline]
 raw_notifier_call_chain+0x3e/0x170 kernel/notifier.c:392
 call_netdevice_notifiers_info net/core/dev.c:1935 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1976 [inline]
 call_netdevice_notifiers net/core/dev.c:1990 [inline]
 netdev_wait_allrefs_any net/core/dev.c:10141 [inline]
 netdev_run_todo+0x8ae/0x1070 net/core/dev.c:10253
 tun_detach drivers/net/tun.c:696 [inline]
 tun_chr_close+0x11f/0x130 drivers/net/tun.c:3445
 __fput+0x3b9/0x820 fs/file_table.c:317
 task_work_run+0x146/0x1c0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:37 [inline]
 do_exit+0x547/0x1eb0 kernel/exit.c:795
 do_group_exit+0x23b/0x2f0 kernel/exit.c:925
 __do_sys_exit_group kernel/exit.c:936 [inline]
 __se_sys_exit_group kernel/exit.c:934 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:934
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f21fa4890e9
Code: Unable to access opcode bytes at RIP 0x7f21fa4890bf.
RSP: 002b:00007ffef2b70fc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000064 RCX: 00007f21fa4890e9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 00007f21fa4e226a R08: 000000000000000c R09: 000055555714a3b8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000016
R13: 00007ffef2b722a0 R14: 000055555714a3b8 R15: 00007ffef2b733a0
 </TASK>

Allocated by task 3619:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 __kasan_slab_alloc+0xb2/0xe0 mm/kasan/common.c:469
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:749 [inline]
 slab_alloc_node mm/slub.c:3217 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x199/0x2f0 mm/slub.c:3242
 kmem_cache_zalloc include/linux/slab.h:704 [inline]
 net_alloc net/core/net_namespace.c:403 [inline]
 copy_net_ns+0x13c/0x5b0 net/core/net_namespace.c:458
 create_new_namespaces+0x4db/0x8e0 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x11e/0x180 kernel/nsproxy.c:226
 ksys_unshare+0x57f/0xb30 kernel/fork.c:3132
 __do_sys_unshare kernel/fork.c:3203 [inline]
 __se_sys_unshare kernel/fork.c:3201 [inline]
 __x64_sys_unshare+0x34/0x40 kernel/fork.c:3201
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 8:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0xd8/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:200 [inline]
 slab_free_hook mm/slub.c:1728 [inline]
 slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1754
 slab_free mm/slub.c:3510 [inline]
 kmem_cache_free+0xc7/0x270 mm/slub.c:3527
 net_free net/core/net_namespace.c:432 [inline]
 cleanup_net+0xb8b/0xc50 net/core/net_namespace.c:615
 process_one_work+0x81c/0xd10 kernel/workqueue.c:2289
 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
 kthread+0x266/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

Last potentially related work creation:
 kasan_save_stack+0x3b/0x60 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:348
 insert_work+0x54/0x3e0 kernel/workqueue.c:1358
 __queue_work+0x969/0xc20 kernel/workqueue.c:1517
 call_timer_fn+0xf5/0x210 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1461 [inline]
 __run_timers+0x7a2/0x980 kernel/time/timer.c:1737
 __do_softirq+0x382/0x793 kernel/softirq.c:558

Second to last potentially related work creation:
 kasan_save_stack+0x3b/0x60 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:348
 insert_work+0x54/0x3e0 kernel/workqueue.c:1358
 __queue_work+0x969/0xc20 kernel/workqueue.c:1517
 call_timer_fn+0xf5/0x210 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1461 [inline]
 __run_timers+0x7a2/0x980 kernel/time/timer.c:1737
 __do_softirq+0x382/0x793 kernel/softirq.c:558

The buggy address belongs to the object at ffff8880266f8000
 which belongs to the cache net_namespace of size 6784
The buggy address is located 616 bytes inside of
 6784-byte region [ffff8880266f8000, ffff8880266f9a80)

The buggy address belongs to the physical page:
page:ffffea000099be00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880266fb700 pfn:0x266f8
head:ffffea000099be00 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff88801cd47ac1
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888140007500
raw: ffff8880266fb700 0000000080040003 00000001ffffffff ffff88801cd47ac1
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3619, tgid 3619 (syz-executor.1), ts 106343775857, free_ts 0
 prep_new_page mm/page_alloc.c:2441 [inline]
 get_page_from_freelist+0x72e/0x7a0 mm/page_alloc.c:4182
 __alloc_pages+0x26c/0x5f0 mm/page_alloc.c:5408
 alloc_slab_page+0x70/0xf0 mm/slub.c:1799
 allocate_slab+0x5e/0x560 mm/slub.c:1944
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x41e/0xcd0 mm/slub.c:3005
 __slab_alloc mm/slub.c:3092 [inline]
 slab_alloc_node mm/slub.c:3183 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x246/0x2f0 mm/slub.c:3242
 kmem_cache_zalloc include/linux/slab.h:704 [inline]
 net_alloc net/core/net_namespace.c:403 [inline]
 copy_net_ns+0x13c/0x5b0 net/core/net_namespace.c:458
 create_new_namespaces+0x4db/0x8e0 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x11e/0x180 kernel/nsproxy.c:226
 ksys_unshare+0x57f/0xb30 kernel/fork.c:3132
 __do_sys_unshare kernel/fork.c:3203 [inline]
 __se_sys_unshare kernel/fork.c:3201 [inline]
 __x64_sys_unshare+0x34/0x40 kernel/fork.c:3201
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8880266f8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880266f8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880266f8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff8880266f8280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880266f8300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================