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BUG: KASAN: use-after-free in __mutex_lock+0x812/0x1300
Read of size 8 at addr ffff888116f240a8 by task khidpd_00065508/16401

CPU: 1 UID: 0 PID: 16401 Comm: khidpd_00065508 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_report+0xba/0x230
 kasan_report+0x117/0x150
 __mutex_lock+0x812/0x1300
 l2cap_unregister_user+0x6a/0x1b0
 hidp_session_thread+0x3cb/0x440
 kthread+0x726/0x8b0
 ret_from_fork+0x51b/0xa40
 ret_from_fork_asm+0x1a/0x30
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888116f25400 pfn:0x116f24
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 017ff00000000000 ffff88823c640d80 ffff88823c640d80 0000000000000000
raw: ffff888116f25400 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x40dc0(GFP_KERNEL|__GFP_ZERO|__GFP_COMP), pid 15833, tgid 15833 (syz-executor), ts 394446024943, free_ts 412651803898
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 alloc_pages_mpol+0x232/0x4a0
 ___kmalloc_large_node+0x4e/0x150
 __kmalloc_large_node_noprof+0x18/0x90
 __kmalloc_noprof+0x4b8/0x7e0
 hci_alloc_dev_priv+0x28/0x2060
 vhci_create_device+0x120/0x650
 vhci_write+0x3ce/0x4a0
 vfs_write+0x61d/0xb90
 ksys_write+0x150/0x270
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 15833 tgid 15833 stack trace:
 __free_frozen_pages+0xbb9/0xd10
 bt_host_release+0x82/0x90
 device_release+0x9e/0x1d0
 kobject_put+0x228/0x560
 vhci_release+0x15a/0x1a0
 __fput+0x44f/0xa70
 task_work_run+0x1d9/0x270
 do_exit+0x69b/0x2310
 do_group_exit+0x21b/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 __pfx_syscall_get_nr+0x0/0x10
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888116f23f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888116f24000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888116f24080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                  ^
 ffff888116f24100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888116f24180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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