syzbot

 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
kobject: kobject_add_internal failed for hci3:201 with -EEXIST, don't try to register things with the same name in the same directory.
Bluetooth: hci3: failed to register connection device
==================================================================
BUG: KASAN: slab-use-after-free in l2cap_conn_ready net/bluetooth/l2cap_core.c:1623 [inline]
BUG: KASAN: slab-use-after-free in l2cap_connect_cfm+0x6d0/0x10c0 net/bluetooth/l2cap_core.c:7304
Read of size 8 at addr ffff88807b718480 by task kworker/u9:4/5950

CPU: 0 UID: 0 PID: 5950 Comm: kworker/u9:4 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: hci3 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:1623 [inline]
 l2cap_connect_cfm+0x6d0/0x10c0 net/bluetooth/l2cap_core.c:7304
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2121
 le_conn_complete_evt+0xfa5/0x14d0 net/bluetooth/hci_event.c:5799
 hci_le_conn_complete_evt+0x187/0x480 net/bluetooth/hci_event.c:5825
 hci_event_func net/bluetooth/hci_event.c:7629 [inline]
 hci_event_packet+0x78f/0x1260 net/bluetooth/hci_event.c:7686
 hci_rx_work+0x45d/0xfc0 net/bluetooth/hci_core.c:4099
 process_one_work+0x94a/0x15d0 kernel/workqueue.c:3267
 process_scheduled_works kernel/workqueue.c:3350 [inline]
 worker_thread+0x9b0/0xee0 kernel/workqueue.c:3431
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5950:
 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:397 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __kmalloc_cache_noprof+0x3e2/0x700 mm/slub.c:5771
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 l2cap_chan_create+0x51/0x790 net/bluetooth/l2cap_core.c:445
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1906 [inline]
 l2cap_sock_new_connection_cb+0x182/0x2e0 net/bluetooth/l2cap_sock.c:1485
 l2cap_connect_cfm+0x367/0x10c0 net/bluetooth/l2cap_core.c:7287
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2121
 le_conn_complete_evt+0xfa5/0x14d0 net/bluetooth/hci_event.c:5799
 hci_le_conn_complete_evt+0x187/0x480 net/bluetooth/hci_event.c:5825
 hci_event_func net/bluetooth/hci_event.c:7629 [inline]
 hci_event_packet+0x78f/0x1260 net/bluetooth/hci_event.c:7686
 hci_rx_work+0x45d/0xfc0 net/bluetooth/hci_core.c:4099
 process_one_work+0x94a/0x15d0 kernel/workqueue.c:3267
 process_scheduled_works kernel/workqueue.c:3350 [inline]
 worker_thread+0x9b0/0xee0 kernel/workqueue.c:3431
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6051:
 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:584
 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:2547 [inline]
 slab_free mm/slub.c:6638 [inline]
 kfree+0x19a/0x6d0 mm/slub.c:6845
 l2cap_sock_cleanup_listen+0xf0/0x450 net/bluetooth/l2cap_sock.c:1468
 l2cap_sock_release+0x6a/0x230 net/bluetooth/l2cap_sock.c:1426
 __sock_release net/socket.c:662 [inline]
 sock_close+0xc3/0x240 net/socket.c:1459
 __fput+0x44c/0xa70 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807b718000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1152 bytes inside of
 freed 2048-byte region [ffff88807b718000, ffff88807b718800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88807b71e000 pfn:0x7b718
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b027000 0000000000000000 0000000000000001
raw: ffff88807b71e000 0000000080080006 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b027000 0000000000000000 0000000000000001
head: ffff88807b71e000 0000000080080006 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0001edc601 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 5902, tgid 5902 (syz-executor), ts 82328884573, free_ts 82293607792
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3920
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5214
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2479
 alloc_slab_page mm/slub.c:3063 [inline]
 allocate_slab+0x96/0x350 mm/slub.c:3236
 new_slab mm/slub.c:3290 [inline]
 ___slab_alloc+0xe94/0x18a0 mm/slub.c:4659
 __slab_alloc+0x65/0x100 mm/slub.c:4778
 __slab_alloc_node mm/slub.c:4854 [inline]
 slab_alloc_node mm/slub.c:5276 [inline]
 __do_kmalloc_node mm/slub.c:5649 [inline]
 __kmalloc_node_track_caller_noprof+0x5d0/0x810 mm/slub.c:5759
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:604
 __alloc_skb+0x142/0x2d0 net/core/skbuff.c:673
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 rtmsg_ifinfo_build_skb+0x84/0x260 net/core/rtnetlink.c:4400
 rtmsg_ifinfo_event net/core/rtnetlink.c:4442 [inline]
 rtmsg_ifinfo+0x8c/0x1a0 net/core/rtnetlink.c:4451
 register_netdevice+0x1712/0x1ae0 net/core/dev.c:11397
 __ip_tunnel_create+0x3e7/0x560 net/ipv4/ip_tunnel.c:268
 ip_tunnel_init_net+0x2ba/0x800 net/ipv4/ip_tunnel.c:1147
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
page last free pid 5890 tgid 5890 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2948
 __slab_free+0x2e7/0x390 mm/slub.c:5970
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:349
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4978 [inline]
 slab_alloc_node mm/slub.c:5288 [inline]
 kmem_cache_alloc_noprof+0x37d/0x700 mm/slub.c:5295
 getname_flags+0xb8/0x540 fs/namei.c:146
 user_path_at+0x24/0x60 fs/namei.c:3214
 __do_sys_chroot fs/open.c:604 [inline]
 __se_sys_chroot+0x90/0x3b0 fs/open.c:598
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88807b718380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807b718400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807b718480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88807b718500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807b718580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================