syzbot

 </TASK>
kobject: kobject_add_internal failed for hci0:201 with -EEXIST, don't try to register things with the same name in the same directory.
Bluetooth: hci0: failed to register connection device
==================================================================
BUG: KASAN: slab-use-after-free in l2cap_sock_new_connection_cb+0x1f9/0x2e0 net/bluetooth/l2cap_sock.c:1525
Read of size 8 at addr ffff88802bb277b0 by task kworker/u9:2/5691

CPU: 0 UID: 0 PID: 5691 Comm: kworker/u9:2 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 l2cap_sock_new_connection_cb+0x1f9/0x2e0 net/bluetooth/l2cap_sock.c:1525
 l2cap_connect_cfm+0x368/0x1560 net/bluetooth/l2cap_core.c:7410
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2139
 le_conn_complete_evt+0x1134/0x16b0 net/bluetooth/hci_event.c:5865
 hci_le_conn_complete_evt+0x187/0x470 net/bluetooth/hci_event.c:5891
 hci_event_func net/bluetooth/hci_event.c:7770 [inline]
 hci_event_packet+0x659/0xef0 net/bluetooth/hci_event.c:7824
 hci_rx_work+0x3ee/0x1040 net/bluetooth/hci_core.c:4077
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5691:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_noprof+0x3e7/0x7b0 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 sk_prot_alloc+0xe7/0x210 net/core/sock.c:2247
 sk_alloc+0x3a/0x390 net/core/sock.c:2303
 bt_sock_alloc+0x3b/0x310 net/bluetooth/af_bluetooth.c:151
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1925 [inline]
 l2cap_sock_new_connection_cb+0xe2/0x2e0 net/bluetooth/l2cap_sock.c:1510
 l2cap_connect_cfm+0x368/0x1560 net/bluetooth/l2cap_core.c:7410
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2139
 le_conn_complete_evt+0x1134/0x16b0 net/bluetooth/hci_event.c:5865
 hci_le_conn_complete_evt+0x187/0x470 net/bluetooth/hci_event.c:5891
 hci_event_func net/bluetooth/hci_event.c:7770 [inline]
 hci_event_packet+0x659/0xef0 net/bluetooth/hci_event.c:7824
 hci_rx_work+0x3ee/0x1040 net/bluetooth/hci_core.c:4077
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6082:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6250 [inline]
 kfree+0x1c5/0x6c0 mm/slub.c:6565
 sk_prot_free net/core/sock.c:2286 [inline]
 __sk_destruct+0x74b/0x9d0 net/core/sock.c:2386
 l2cap_sock_cleanup_listen+0xe0/0x440 net/bluetooth/l2cap_sock.c:1490
 l2cap_sock_release+0x6e/0x270 net/bluetooth/l2cap_sock.c:1451
 __sock_release net/socket.c:722 [inline]
 sock_close+0xc3/0x240 net/socket.c:1514
 __fput+0x461/0xa70 fs/file_table.c:510
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802bb27000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1968 bytes inside of
 freed 2048-byte region [ffff88802bb27000, ffff88802bb27800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2bb20
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88801a010000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88801a010000 dead000000000100 dead000000000122
head: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 0080000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
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 5745, tgid 5745 (syz-executor), ts 102802814478, free_ts 100732938218
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x27c8/0x2840 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x33c/0x3d0 mm/slub.c:7255
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x373/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __kmalloc_cache_noprof+0x44e/0x690 mm/slub.c:5414
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 rxrpc_alloc_connection+0x7b/0x600 net/rxrpc/conn_object.c:62
 rxrpc_prealloc_service_connection+0x26/0x2f0 net/rxrpc/conn_service.c:123
 rxrpc_service_prealloc_one+0x2f5/0xe20 net/rxrpc/call_accept.c:86
 afs_charge_preallocation+0x394/0x4e0 fs/afs/rxrpc.c:758
 afs_open_socket+0x33c/0x3f0 fs/afs/rxrpc.c:112
 afs_net_init+0x6ce/0x8f0 fs/afs/main.c:116
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 setup_net+0x118/0x340 net/core/net_namespace.c:446
 copy_net_ns+0x50e/0x730 net/core/net_namespace.c:579
page last free pid 5760 tgid 5757 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0xfa6/0x10f0 mm/page_alloc.c:2943
 __slab_free+0x252/0x2a0 mm/slub.c:5612
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_node_noprof+0x22a/0x6e0 mm/slub.c:4950
 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702
 alloc_skb include/linux/skbuff.h:1383 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:519 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:496 [inline]
 vhci_write+0xc0/0x4a0 drivers/bluetooth/hci_vhci.c:616
 do_iter_readv_writev+0x62b/0x8d0 fs/read_write.c:-1
 vfs_writev+0x345/0x9a0 fs/read_write.c:1059
 do_writev+0x15a/0x2e0 fs/read_write.c:1105
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88802bb27680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802bb27700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802bb27780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff88802bb27800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802bb27880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================