==================================================================
BUG: KASAN: use-after-free in notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75
Read of size 8 at addr ffff88807bd71ea8 by task syz-executor.1/3636

CPU: 1 PID: 3636 Comm: syz-executor.1 Not tainted 6.0.0-rc4-syzkaller-01170-g3cae32b480d1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:317 [inline]
 print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
 kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
 notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75
 call_netdevice_notifiers_info+0x86/0x130 net/core/dev.c:1942
 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline]
 call_netdevice_notifiers net/core/dev.c:1997 [inline]
 netdev_wait_allrefs_any net/core/dev.c:10250 [inline]
 netdev_run_todo+0xbc2/0x1100 net/core/dev.c:10364
 tun_detach drivers/net/tun.c:704 [inline]
 tun_chr_close+0xe0/0x180 drivers/net/tun.c:3455
 __fput+0x277/0x9d0 fs/file_table.c:320
 task_work_run+0xdd/0x1a0 kernel/task_work.c:177
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xad5/0x29b0 kernel/exit.c:795
 do_group_exit+0xd2/0x2f0 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+0x3a/0x50 kernel/exit.c:934
 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+0x63/0xcd
RIP: 0033:0x7f26ec68a669
Code: Unable to access opcode bytes at RIP 0x7f26ec68a63f.
RSP: 002b:00007ffc9aa18588 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007ffc9aa18730 RCX: 00007f26ec68a669
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000043
RBP: 0000000000000000 R08: 0000000000000025 R09: 00007ffc9aa18730
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f26ec6e5531
R13: 000000000000001c R14: 000000000000000d R15: 00007ffc9aa18770
 </TASK>

Allocated by task 3636:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:437 [inline]
 __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:470
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:727 [inline]
 slab_alloc_node mm/slub.c:3243 [inline]
 slab_alloc mm/slub.c:3251 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3258 [inline]
 kmem_cache_alloc+0x267/0x3b0 mm/slub.c:3268
 kmem_cache_zalloc include/linux/slab.h:723 [inline]
 net_alloc net/core/net_namespace.c:404 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:459
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:227
 ksys_unshare+0x445/0x920 kernel/fork.c:3183
 __do_sys_unshare kernel/fork.c:3254 [inline]
 __se_sys_unshare kernel/fork.c:3252 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3252
 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+0x63/0xcd

Freed by task 20015:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:45
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:367 [inline]
 ____kasan_slab_free+0x166/0x1c0 mm/kasan/common.c:329
 kasan_slab_free include/linux/kasan.h:200 [inline]
 slab_free_hook mm/slub.c:1754 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1780
 slab_free mm/slub.c:3534 [inline]
 kmem_cache_free+0xeb/0x5b0 mm/slub.c:3551
 net_free net/core/net_namespace.c:433 [inline]
 net_free net/core/net_namespace.c:429 [inline]
 cleanup_net+0x8ba/0xb00 net/core/net_namespace.c:616
 process_one_work+0x991/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e4/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x625/0x1210 kernel/workqueue.c:1517
 call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1514 [inline]
 __run_timers.part.0+0x4a3/0xa80 kernel/time/timer.c:1790
 __run_timers kernel/time/timer.c:1768 [inline]
 run_timer_softirq+0x152/0x1d0 kernel/time/timer.c:1805
 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571

Second to last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x625/0x1210 kernel/workqueue.c:1517
 call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1514 [inline]
 __run_timers.part.0+0x4a3/0xa80 kernel/time/timer.c:1790
 __run_timers kernel/time/timer.c:1768 [inline]
 run_timer_softirq+0x152/0x1d0 kernel/time/timer.c:1805
 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571

The buggy address belongs to the object at ffff88807bd71c40
 which belongs to the cache net_namespace of size 6976
The buggy address is located 616 bytes inside of
 6976-byte region [ffff88807bd71c40, ffff88807bd73780)

The buggy address belongs to the physical page:
page:ffffea0001ef5c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88807bd73880 pfn:0x7bd70
head:ffffea0001ef5c00 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff8880786e7fc1
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea0001317600 dead000000000003 ffff8881400073c0
raw: ffff88807bd73880 0000000080040003 00000001ffffffff ffff8880786e7fc1
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 3639, tgid 3639 (syz-executor.2), ts 128536929831, free_ts 128512600865
 prep_new_page mm/page_alloc.c:2532 [inline]
 get_page_from_freelist+0x109b/0x2ce0 mm/page_alloc.c:4283
 __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5515
 alloc_pages+0x1a6/0x270 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:1824 [inline]
 allocate_slab+0x27e/0x3d0 mm/slub.c:1969
 new_slab mm/slub.c:2029 [inline]
 ___slab_alloc+0x7f1/0xe10 mm/slub.c:3031
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
 slab_alloc_node mm/slub.c:3209 [inline]
 slab_alloc mm/slub.c:3251 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3258 [inline]
 kmem_cache_alloc+0x38c/0x3b0 mm/slub.c:3268
 kmem_cache_zalloc include/linux/slab.h:723 [inline]
 net_alloc net/core/net_namespace.c:404 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:459
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:227
 ksys_unshare+0x445/0x920 kernel/fork.c:3183
 __do_sys_unshare kernel/fork.c:3254 [inline]
 __se_sys_unshare kernel/fork.c:3252 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3252
 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+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1449 [inline]
 free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1499
 free_unref_page_prepare mm/page_alloc.c:3380 [inline]
 free_unref_page+0x19/0x4d0 mm/page_alloc.c:3476
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:447
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:727 [inline]
 slab_alloc_node mm/slub.c:3243 [inline]
 slab_alloc mm/slub.c:3251 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3258 [inline]
 kmem_cache_alloc_lru+0x376/0x720 mm/slub.c:3275
 __d_alloc+0x32/0x960 fs/dcache.c:1769
 d_alloc+0x4a/0x230 fs/dcache.c:1849
 d_alloc_parallel+0xe4/0x1400 fs/dcache.c:2647
 __lookup_slow+0x193/0x460 fs/namei.c:1670
 lookup_slow fs/namei.c:1702 [inline]
 walk_component+0x33f/0x5a0 fs/namei.c:1993
 link_path_walk.part.0+0x74e/0xe20 fs/namei.c:2320
 link_path_walk fs/namei.c:2245 [inline]
 path_openat+0x262/0x28f0 fs/namei.c:3687
 do_filp_open+0x1b6/0x400 fs/namei.c:3718
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1311
 do_sys_open fs/open.c:1327 [inline]
 __do_sys_openat fs/open.c:1343 [inline]
 __se_sys_openat fs/open.c:1338 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1338

Memory state around the buggy address:
 ffff88807bd71d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807bd71e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807bd71e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88807bd71f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807bd71f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================