==================================================================
BUG: KASAN: use-after-free in device_for_each_child+0xa7/0x170 drivers/base/core.c:4036
Read of size 8 at addr ffff88802e49d5f8 by task kbnepd bnep0/7196

CPU: 1 PID: 7196 Comm: kbnepd bnep0 Not tainted 6.9.0-rc4-next-20240418-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 device_for_each_child+0xa7/0x170 drivers/base/core.c:4036
 pm_runtime_set_memalloc_noio+0x114/0x260 drivers/base/power/runtime.c:248
 netdev_unregister_kobject+0x178/0x250 net/core/net-sysfs.c:2106
 unregister_netdevice_many_notify+0x11dd/0x16e0 net/core/dev.c:11208
 unregister_netdevice_many net/core/dev.c:11236 [inline]
 unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11115
 unregister_netdevice include/linux/netdevice.h:3118 [inline]
 unregister_netdev+0x1c/0x30 net/core/dev.c:11254
 bnep_session+0x2e09/0x3000 net/bluetooth/bnep/core.c:525
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x4 pfn:0x2e49d
flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff)
raw: 00fff80000000000 ffffea0000b92788 ffffea0000b92708 0000000000000000
raw: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x140dc0(GFP_USER|__GFP_COMP|__GFP_ZERO), pid 6950, tgid 1771116106 (syz-executor.4), ts 6950, free_ts 157197072097
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1476
 prep_new_page mm/page_alloc.c:1484 [inline]
 get_page_from_freelist+0x2ce2/0x2d90 mm/page_alloc.c:3446
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4704
 __alloc_pages_node_noprof include/linux/gfp.h:244 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:271 [inline]
 __kmalloc_large_node+0x91/0x1f0 mm/slub.c:4023
 __do_kmalloc_node mm/slub.c:4066 [inline]
 __kmalloc_noprof+0x2b1/0x400 mm/slub.c:4091
 kmalloc_noprof include/linux/slab.h:664 [inline]
 kzalloc_noprof include/linux/slab.h:778 [inline]
 hci_alloc_dev_priv+0x27/0x2030 net/bluetooth/hci_core.c:2507
 hci_alloc_dev include/net/bluetooth/hci_core.h:1685 [inline]
 __vhci_create_device drivers/bluetooth/hci_vhci.c:406 [inline]
 vhci_create_device+0x12e/0x720 drivers/bluetooth/hci_vhci.c:480
 vhci_get_user drivers/bluetooth/hci_vhci.c:537 [inline]
 vhci_write+0x3cb/0x480 drivers/bluetooth/hci_vhci.c:617
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa72/0xc90 fs/read_write.c:590
 ksys_write+0x1a0/0x2c0 fs/read_write.c:643
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6950 tgid 6950 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1096 [inline]
 free_unref_page+0xd22/0xea0 mm/page_alloc.c:2609
 __folio_put+0x3b9/0x620 mm/swap.c:129
 folio_put include/linux/mm.h:1509 [inline]
 free_large_kmalloc+0x105/0x1c0 mm/slub.c:4485
 kfree+0x1c4/0x350 mm/slub.c:4508
 hci_release_dev+0x1516/0x16a0 net/bluetooth/hci_core.c:2840
 bt_host_release+0x83/0x90 net/bluetooth/hci_sysfs.c:94
 device_release+0x99/0x1c0
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22f/0x480 lib/kobject.c:737
 vhci_release+0x8b/0xd0 drivers/bluetooth/hci_vhci.c:675
 __fput+0x406/0x8b0 fs/file_table.c:422
 task_work_run+0x24f/0x310 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa1b/0x27e0 kernel/exit.c:877
 do_group_exit+0x207/0x2c0 kernel/exit.c:1026
 __do_sys_exit_group kernel/exit.c:1037 [inline]
 __se_sys_exit_group kernel/exit.c:1035 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1035
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88802e49d480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88802e49d500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88802e49d580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff88802e49d600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88802e49d680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================