syzbot

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
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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+0x6df/0x1030 net/bluetooth/l2cap_core.c:7275
Read of size 8 at addr ffff888079ae9480 by task kworker/u5:5/5915

CPU: 1 PID: 5915 Comm: kworker/u5:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 l2cap_conn_ready net/bluetooth/l2cap_core.c:1623 [inline]
 l2cap_connect_cfm+0x6df/0x1030 net/bluetooth/l2cap_core.c:7275
 hci_connect_cfm+0x8f/0x130 include/net/bluetooth/hci_core.h:1970
 le_conn_complete_evt+0xcd0/0x1220 net/bluetooth/hci_event.c:5752
 hci_le_conn_complete_evt+0x187/0x440 net/bluetooth/hci_event.c:5778
 hci_event_func net/bluetooth/hci_event.c:7420 [inline]
 hci_event_packet+0x795/0x1210 net/bluetooth/hci_event.c:7475
 hci_rx_work+0x43a/0xd80 net/bluetooth/hci_core.c:4018
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Allocated by task 5915:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 l2cap_chan_create+0x50/0x760 net/bluetooth/l2cap_core.c:445
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1890 [inline]
 l2cap_sock_new_connection_cb+0x182/0x2b0 net/bluetooth/l2cap_sock.c:1469
 l2cap_connect_cfm+0x375/0x1030 net/bluetooth/l2cap_core.c:7258
 hci_connect_cfm+0x8f/0x130 include/net/bluetooth/hci_core.h:1970
 le_conn_complete_evt+0xcd0/0x1220 net/bluetooth/hci_event.c:5752
 hci_le_conn_complete_evt+0x187/0x440 net/bluetooth/hci_event.c:5778
 hci_event_func net/bluetooth/hci_event.c:7420 [inline]
 hci_event_packet+0x795/0x1210 net/bluetooth/hci_event.c:7475
 hci_rx_work+0x43a/0xd80 net/bluetooth/hci_core.c:4018
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Freed by task 6017:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1811 [inline]
 slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
 l2cap_sock_cleanup_listen+0xea/0x3e0 net/bluetooth/l2cap_sock.c:1452
 l2cap_sock_release+0x6a/0x1e0 net/bluetooth/l2cap_sock.c:1410
 __sock_release net/socket.c:659 [inline]
 sock_close+0xbd/0x230 net/socket.c:1421
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 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+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888079ae9000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1152 bytes inside of
 freed 2048-byte region [ffff888079ae9000, ffff888079ae9800)

The buggy address belongs to the physical page:
page:ffffea0001e6ba00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888079aef000 pfn:0x79ae8
head:ffffea0001e6ba00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017842000 ffffea00017a7400 0000000000000002
raw: ffff888079aef000 0000000080080005 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5865, tgid 5865 (syz-executor), ts 95482621919, free_ts 95456972388
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2081
 ___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa4/0x240 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 ipt_alloc_initial_table+0x6e/0x610 net/ipv4/netfilter/ip_tables.c:36
 iptable_mangle_table_init+0x1b/0x60 net/ipv4/netfilter/iptable_mangle.c:88
 xt_find_table_lock+0x306/0x3e0 net/netfilter/x_tables.c:1259
 xt_request_find_table_lock+0x26/0x100 net/netfilter/x_tables.c:1284
 get_info net/ipv4/netfilter/ip_tables.c:963 [inline]
 do_ipt_get_ctl+0x729/0x1140 net/ipv4/netfilter/ip_tables.c:1659
 nf_getsockopt+0x262/0x280 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x1c1/0x210 net/ipv4/ip_sockglue.c:1790
 do_sock_getsockopt+0x368/0x440 net/socket.c:2384
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x31d/0x410 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x11e/0x2e0 mm/slub.c:3519
 getname_flags+0xbb/0x500 fs/namei.c:140
 getname fs/namei.c:219 [inline]
 __do_sys_mkdirat fs/namei.c:4151 [inline]
 __se_sys_mkdirat fs/namei.c:4149 [inline]
 __x64_sys_mkdirat+0x7c/0xa0 fs/namei.c:4149
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888079ae9380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888079ae9400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888079ae9480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888079ae9500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888079ae9580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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