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kobject_add_internal failed for hci5:201 with -EEXIST, don't try to register things with the same name in the same directory.
Bluetooth: hci5: failed to register connection device
==================================================================
BUG: KASAN: use-after-free in l2cap_sock_new_connection_cb+0x1f5/0x2a0 net/bluetooth/l2cap_sock.c:1527
Read of size 8 at addr ffff888017765548 by task kworker/u5:0/13678

CPU: 0 PID: 13678 Comm: kworker/u5:0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: hci5 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 l2cap_sock_new_connection_cb+0x1f5/0x2a0 net/bluetooth/l2cap_sock.c:1527
 l2cap_connect_cfm+0x35f/0x1120 net/bluetooth/l2cap_core.c:8421
 hci_connect_cfm+0x8f/0x130 include/net/bluetooth/hci_core.h:1817
 le_conn_complete_evt+0x10ef/0x1670 net/bluetooth/hci_event.c:5882
 hci_le_conn_complete_evt+0x183/0x440 net/bluetooth/hci_event.c:5908
 hci_event_func net/bluetooth/hci_event.c:7419 [inline]
 hci_event_packet+0x7b9/0x1280 net/bluetooth/hci_event.c:7474
 hci_rx_work+0x3eb/0xd40 net/bluetooth/hci_core.c:4109
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 13678:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc+0xb0/0x240 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 sk_prot_alloc+0xe7/0x210 net/core/sock.c:2052
 sk_alloc+0x36/0x340 net/core/sock.c:2108
 bt_sock_alloc+0x36/0x130 net/bluetooth/af_bluetooth.c:148
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1927 [inline]
 l2cap_sock_new_connection_cb+0xde/0x2a0 net/bluetooth/l2cap_sock.c:1512
 l2cap_connect_cfm+0x35f/0x1120 net/bluetooth/l2cap_core.c:8421
 hci_connect_cfm+0x8f/0x130 include/net/bluetooth/hci_core.h:1817
 le_conn_complete_evt+0x10ef/0x1670 net/bluetooth/hci_event.c:5882
 hci_le_conn_complete_evt+0x183/0x440 net/bluetooth/hci_event.c:5908
 hci_event_func net/bluetooth/hci_event.c:7419 [inline]
 hci_event_packet+0x7b9/0x1280 net/bluetooth/hci_event.c:7474
 hci_rx_work+0x3eb/0xd40 net/bluetooth/hci_core.c:4109
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 19449:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 sk_prot_free net/core/sock.c:2091 [inline]
 __sk_destruct+0x4ba/0x650 net/core/sock.c:2177
 l2cap_sock_cleanup_listen+0xda/0x270 net/bluetooth/l2cap_sock.c:1492
 l2cap_sock_release+0x66/0x1e0 net/bluetooth/l2cap_sock.c:1453
 __sock_release net/socket.c:654 [inline]
 sock_close+0xd5/0x240 net/socket.c:1399
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 get_signal+0x11a6/0x1350 kernel/signal.c:2648
 arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
 call_rcu+0x14f/0x990 kernel/rcu/tree.c:2849
 netdev_for_each_tx_queue include/linux/netdevice.h:2465 [inline]
 dev_shutdown+0x92/0x440 net/sched/sch_generic.c:1465
 unregister_netdevice_many_notify+0xa76/0x19c0 net/core/dev.c:11014
 unregister_netdevice_many net/core/dev.c:11077 [inline]
 unregister_netdevice_queue+0x328/0x370 net/core/dev.c:10960
 unregister_netdevice include/linux/netdevice.h:3075 [inline]
 __tun_detach+0xd4a/0x1500 drivers/net/tun.c:685
 tun_detach drivers/net/tun.c:701 [inline]
 tun_chr_close+0x109/0x1b0 drivers/net/tun.c:3492
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Second to last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
 call_rcu+0x14f/0x990 kernel/rcu/tree.c:2849
 netdev_for_each_tx_queue include/linux/netdevice.h:2465 [inline]
 dev_shutdown+0x92/0x440 net/sched/sch_generic.c:1465
 unregister_netdevice_many_notify+0xa76/0x19c0 net/core/dev.c:11014
 unregister_netdevice_many net/core/dev.c:11077 [inline]
 unregister_netdevice_queue+0x328/0x370 net/core/dev.c:10960
 unregister_netdevice include/linux/netdevice.h:3075 [inline]
 __tun_detach+0xd4a/0x1500 drivers/net/tun.c:685
 tun_detach drivers/net/tun.c:701 [inline]
 tun_chr_close+0x109/0x1b0 drivers/net/tun.c:3492
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 get_signal+0x11a6/0x1350 kernel/signal.c:2648
 arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888017765000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1352 bytes inside of
 2048-byte region [ffff888017765000, ffff888017765800)

The buggy address belongs to the physical page:
page:ffffea00005dd800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17760
head:ffffea00005dd800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888017442000
raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
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 4278, tgid 4278 (syz-executor), ts 80089979435, free_ts 80088719466
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2559
 prep_new_page mm/page_alloc.c:2566 [inline]
 get_page_from_freelist+0x1a1e/0x1ab0 mm/page_alloc.c:4357
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5657
 alloc_slab_page+0x5d/0x160 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1997
 ___slab_alloc+0xbc6/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc+0xa0/0x240 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 sk_prot_alloc+0xe7/0x210 net/core/sock.c:2052
 sk_alloc+0x36/0x340 net/core/sock.c:2108
 __netlink_create+0x6b/0x2d0 net/netlink/af_netlink.c:629
 __netlink_kernel_create+0x144/0x7b0 net/netlink/af_netlink.c:1997
 netlink_kernel_create include/linux/netlink.h:62 [inline]
 genl_pernet_init+0xb6/0x170 net/netlink/genetlink.c:1457
 ops_init+0x355/0x5f0 net/core/net_namespace.c:138
 setup_net+0x4f2/0xbd0 net/core/net_namespace.c:336
 copy_net_ns+0x348/0x5b0 net/core/net_namespace.c:508
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1486 [inline]
 free_pcp_prepare mm/page_alloc.c:1536 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3413
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3508
 free_large_kmalloc+0xfd/0x190 mm/slab_common.c:913
 skb_free_head net/core/skbuff.c:762 [inline]
 skb_release_data+0x5db/0x7c0 net/core/skbuff.c:791
 skb_release_all net/core/skbuff.c:856 [inline]
 __kfree_skb net/core/skbuff.c:870 [inline]
 consume_skb+0xa2/0x100 net/core/skbuff.c:1035
 netlink_recvmsg+0x5e3/0xe00 net/netlink/af_netlink.c:1950
 ____sys_recvmsg+0x2cb/0x5e0 net/socket.c:-1
 ___sys_recvmsg+0x212/0x590 net/socket.c:2779
 __sys_recvmsg net/socket.c:2809 [inline]
 __do_sys_recvmsg net/socket.c:2819 [inline]
 __se_sys_recvmsg net/socket.c:2816 [inline]
 __x64_sys_recvmsg+0x205/0x2e0 net/socket.c:2816
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888017765400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888017765480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888017765500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff888017765580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888017765600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================