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BUG: KASAN: slab-use-after-free in hci_chan_del+0x3b/0x1b0 net/bluetooth/hci_conn.c:2853
Read of size 8 at addr ffff888029eae318 by task syz.8.4652/20817

CPU: 0 UID: 0 PID: 20817 Comm: syz.8.4652 Not tainted 6.14.0-rc1-next-20250207-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 hci_chan_del+0x3b/0x1b0 net/bluetooth/hci_conn.c:2853
 l2cap_conn_free net/bluetooth/l2cap_core.c:1816 [inline]
 kref_put include/linux/kref.h:65 [inline]
 l2cap_conn_put+0x70/0xe0 net/bluetooth/l2cap_core.c:1830
 l2cap_sock_shutdown+0xa8a/0x1020 net/bluetooth/l2cap_sock.c:1377
 l2cap_sock_release+0x79/0x1d0 net/bluetooth/l2cap_sock.c:1416
 __sock_release net/socket.c:647 [inline]
 sock_close+0xbc/0x240 net/socket.c:1398
 __fput+0x3e9/0x9f0 fs/file_table.c:464
 task_work_run+0x24f/0x310 kernel/task_work.c:227
 get_signal+0x15f7/0x1750 kernel/signal.c:2809
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa619f8cde9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa61ad67038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffffc RBX: 00007fa61a1a6080 RCX: 00007fa619f8cde9
RDX: 000000000000000d RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007fa61a00e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fa61a1a6080 R15: 00007ffe7c556a68
 </TASK>

Allocated by task 20814:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4339
 kmalloc_noprof include/linux/slab.h:902 [inline]
 kzalloc_noprof include/linux/slab.h:1038 [inline]
 hci_chan_create+0xc8/0x310 net/bluetooth/hci_conn.c:2838
 l2cap_conn_add+0x69/0x8e0 net/bluetooth/l2cap_core.c:6864
 l2cap_chan_connect+0x623/0xeb0 net/bluetooth/l2cap_core.c:7059
 l2cap_sock_connect+0x5c9/0x800 net/bluetooth/l2cap_sock.c:256
 __sys_connect_file net/socket.c:2045 [inline]
 __sys_connect+0x288/0x2d0 net/socket.c:2064
 __do_sys_connect net/socket.c:2070 [inline]
 __se_sys_connect net/socket.c:2067 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2067
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 16176:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2367 [inline]
 slab_free mm/slub.c:4623 [inline]
 kfree+0x196/0x430 mm/slub.c:4816
 hci_chan_list_flush net/bluetooth/hci_conn.c:2878 [inline]
 hci_conn_cleanup net/bluetooth/hci_conn.c:149 [inline]
 hci_conn_del+0x4b5/0xc40 net/bluetooth/hci_conn.c:1164
 hci_conn_failed+0x319/0x400 net/bluetooth/hci_conn.c:1267
 hci_abort_conn_sync+0x56c/0x11f0 net/bluetooth/hci_sync.c:5588
 hci_cmd_sync_work+0x22b/0x400 net/bluetooth/hci_sync.c:332
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff888029eae300
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
 freed 128-byte region [ffff888029eae300, ffff888029eae380)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29eae
anon flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801ac41a00 ffffea00012f4180 dead000000000005
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 11, tgid 11 (kworker/u8:0), ts 92970268541, free_ts 92968563759
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1629
 prep_new_page mm/page_alloc.c:1637 [inline]
 get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3555
 __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4817
 alloc_pages_mpol+0x311/0x660 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:2437 [inline]
 allocate_slab+0x8f/0x3a0 mm/slub.c:2601
 new_slab mm/slub.c:2654 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3840
 __slab_alloc+0x58/0xa0 mm/slub.c:3930
 __slab_alloc_node mm/slub.c:4005 [inline]
 slab_alloc_node mm/slub.c:4166 [inline]
 __kmalloc_cache_noprof+0x27b/0x390 mm/slub.c:4334
 kmalloc_noprof include/linux/slab.h:902 [inline]
 __hw_addr_create net/core/dev_addr_lists.c:60 [inline]
 __hw_addr_add_ex+0x1a8/0x610 net/core/dev_addr_lists.c:118
 __dev_mc_add net/core/dev_addr_lists.c:868 [inline]
 dev_mc_add+0xa3/0x110 net/core/dev_addr_lists.c:886
 igmp6_group_added+0x1a4/0x710 net/ipv6/mcast.c:684
 __ipv6_dev_mc_inc+0x8da/0xac0 net/ipv6/mcast.c:988
 addrconf_join_solict net/ipv6/addrconf.c:2240 [inline]
 addrconf_dad_begin net/ipv6/addrconf.c:4095 [inline]
 addrconf_dad_work+0x44f/0x16a0 net/ipv6/addrconf.c:4223
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x7a9/0x920 kernel/kthread.c:464
page last free pid 11 tgid 11 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1205 [inline]
 free_frozen_pages+0xe0d/0x10e0 mm/page_alloc.c:2738
 rcu_do_batch kernel/rcu/tree.c:2546 [inline]
 rcu_core+0xaaa/0x17a0 kernel/rcu/tree.c:2802
 handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561
 do_softirq+0x11b/0x1e0 kernel/softirq.c:462
 __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:389
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 addrconf_dad_work+0x220/0x16a0 net/ipv6/addrconf.c:4220
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff888029eae200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888029eae280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888029eae300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888029eae380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888029eae400: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
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