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BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0xa7/0xf0
Read of size 1 at addr ffff88811aae42f0 by task kworker/1:0/24

CPU: 1 UID: 0 PID: 24 Comm: kworker/1:0 Not tainted 6.16.0-rc3-syzkaller-00159-g223e2288f4b8 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events l2cap_chan_timeout
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_report+0xd2/0x2b0
 kasan_report+0x118/0x150
 __kasan_check_byte+0x2a/0x40
 lock_acquire+0x8d/0x360
 _raw_spin_lock_irqsave+0xa7/0xf0
 __mutex_lock+0x3dd/0xe80
 l2cap_chan_timeout+0x63/0x390
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 8941:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 l2cap_conn_add+0xaa/0x8d0
 l2cap_chan_connect+0x6c8/0xe30
 l2cap_sock_connect+0x5c5/0x7a0
 kernel_connect+0x116/0x180
 rfcomm_dlc_open+0x8fe/0xed0
 rfcomm_sock_connect+0x2f7/0x610
 __sys_connect+0x316/0x440
 __x64_sys_connect+0x7a/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 8804:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x62/0x70
 kfree+0x18e/0x440
 hci_conn_hash_flush+0x10d/0x230
 hci_dev_close_sync+0xaef/0x1330
 hci_unregister_dev+0x21a/0x510
 vhci_release+0x80/0xd0
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x22e0
 do_group_exit+0x21c/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x21ba/0x21c0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88811aae4000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 752 bytes inside of
 freed 1024-byte region [ffff88811aae4000, ffff88811aae4400)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88811aae6800 pfn:0x11aae0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000240(workingset|head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000240 ffff88801a441dc0 ffffea000404a810 ffffea00046d6a10
raw: ffff88811aae6800 0000000000100009 00000000f5000000 0000000000000000
head: 057ff00000000240 ffff88801a441dc0 ffffea000404a810 ffffea00046d6a10
head: ffff88811aae6800 0000000000100009 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea00046ab801 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5814, tgid 5814 (syz-executor), ts 56192599989, free_ts 0
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x8a/0x3b0
 ___slab_alloc+0xbfc/0x1480
 __kmalloc_cache_noprof+0x296/0x3d0
 batadv_hard_if_event+0x11b7/0x1a50
 notifier_call_chain+0x1b6/0x3e0
 register_netdevice+0x1608/0x1ae0
 veth_newlink+0x42f/0xa50
 rtnl_newlink_create+0x310/0xb00
 rtnl_newlink+0x16d6/0x1c70
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x75b/0x8d0
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88811aae4180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811aae4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811aae4280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff88811aae4300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811aae4380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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