sysfs: cannot create duplicate filename '/devices/virtual/bluetooth/hci0/hci0:201'
CPU: 0 UID: 0 PID: 5322 Comm: kworker/u5:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 sysfs_warn_dup fs/sysfs/dir.c:30 [inline]
 sysfs_create_dir_ns+0x259/0x280 fs/sysfs/dir.c:63
 create_dir lib/kobject.c:73 [inline]
 kobject_add_internal+0x6a8/0xca0 lib/kobject.c:240
 kobject_add_varg lib/kobject.c:374 [inline]
 kobject_add+0x155/0x220 lib/kobject.c:426
 device_add+0x408/0xb50 drivers/base/core.c:3627
 hci_conn_add_sysfs+0xd5/0x1e0 net/bluetooth/hci_sysfs.c:48
 le_conn_complete_evt+0xf1d/0x1420 net/bluetooth/hci_event.c:5816
 hci_le_conn_complete_evt+0x187/0x450 net/bluetooth/hci_event.c:5847
 hci_event_func net/bluetooth/hci_event.c:7716 [inline]
 hci_event_packet+0x78f/0x1200 net/bluetooth/hci_event.c:7773
 hci_rx_work+0x42b/0xf20 net/bluetooth/hci_core.c:4076
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </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_conn_ready net/bluetooth/l2cap_core.c:1624 [inline]
BUG: KASAN: slab-use-after-free in l2cap_connect_cfm+0x6e4/0x1060 net/bluetooth/l2cap_core.c:7305
Read of size 8 at addr ffff888042e15480 by task kworker/u5:2/5322

CPU: 0 UID: 0 PID: 5322 Comm: kworker/u5:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 l2cap_conn_ready net/bluetooth/l2cap_core.c:1624 [inline]
 l2cap_connect_cfm+0x6e4/0x1060 net/bluetooth/l2cap_core.c:7305
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2131
 le_conn_complete_evt+0xf65/0x1420 net/bluetooth/hci_event.c:5821
 hci_le_conn_complete_evt+0x187/0x450 net/bluetooth/hci_event.c:5847
 hci_event_func net/bluetooth/hci_event.c:7716 [inline]
 hci_event_packet+0x78f/0x1200 net/bluetooth/hci_event.c:7773
 hci_rx_work+0x42b/0xf20 net/bluetooth/hci_core.c:4076
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Allocated by task 5322:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __kmalloc_cache_noprof+0x3d5/0x6f0 mm/slub.c:5771
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 l2cap_chan_create+0x50/0x760 net/bluetooth/l2cap_core.c:445
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1906 [inline]
 l2cap_sock_new_connection_cb+0x182/0x2b0 net/bluetooth/l2cap_sock.c:1485
 l2cap_connect_cfm+0x37a/0x1060 net/bluetooth/l2cap_core.c:7288
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2131
 le_conn_complete_evt+0xf65/0x1420 net/bluetooth/hci_event.c:5821
 hci_le_conn_complete_evt+0x187/0x450 net/bluetooth/hci_event.c:5847
 hci_event_func net/bluetooth/hci_event.c:7716 [inline]
 hci_event_packet+0x78f/0x1200 net/bluetooth/hci_event.c:7773
 hci_rx_work+0x42b/0xf20 net/bluetooth/hci_core.c:4076
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Freed by task 5344:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6663 [inline]
 kfree+0x1c0/0x660 mm/slub.c:6871
 l2cap_sock_cleanup_listen+0xea/0x3e0 net/bluetooth/l2cap_sock.c:1468
 l2cap_sock_release+0x6a/0x210 net/bluetooth/l2cap_sock.c:1426
 __sock_release net/socket.c:653 [inline]
 sock_close+0xc3/0x240 net/socket.c:1446
 __fput+0x44c/0xa70 fs/file_table.c:468
 task_work_run+0x1d4/0x260 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:44 [inline]
 exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888042e15000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1152 bytes inside of
 freed 2048-byte region [ffff888042e15000, ffff888042e15800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x42e10
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801a042000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff88801a042000 dead000000000122 0000000000000000
head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 04fff00000000003 ffffea00010b8401 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 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 4725, tgid 4725 (klogd), ts 86278205740, free_ts 86104710127
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1845
 prep_new_page mm/page_alloc.c:1853 [inline]
 get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3879
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3b0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xf2b/0x1960 mm/slub.c:4651
 __slab_alloc+0x65/0x100 mm/slub.c:4774
 __slab_alloc_node mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:5246 [inline]
 __kmalloc_cache_noprof+0x411/0x6f0 mm/slub.c:5766
 kmalloc_noprof include/linux/slab.h:957 [inline]
 syslog_print+0xd2/0x590 kernel/printk/printk.c:1583
 do_syslog+0x544/0x760 kernel/printk/printk.c:1761
 __do_sys_syslog kernel/printk/printk.c:1853 [inline]
 __se_sys_syslog kernel/printk/printk.c:1851 [inline]
 __x64_sys_syslog+0x7c/0x90 kernel/printk/printk.c:1851
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5033 tgid 5033 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2901
 __slab_free+0x21b/0x2a0 mm/slub.c:5999
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:352
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4948 [inline]
 slab_alloc_node mm/slub.c:5258 [inline]
 kmem_cache_alloc_node_noprof+0x433/0x710 mm/slub.c:5310
 __alloc_skb+0x255/0x430 net/core/skbuff.c:679
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6712
 sock_alloc_send_pskb+0x84d/0x980 net/core/sock.c:2995
 unix_dgram_sendmsg+0x501/0x18c0 net/unix/af_unix.c:2130
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:733
 __sys_sendto+0x3bd/0x520 net/socket.c:2197
 __do_sys_sendto net/socket.c:2204 [inline]
 __se_sys_sendto net/socket.c:2200 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2200
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888042e15380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888042e15400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888042e15480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888042e15500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888042e15580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================