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BUG: KASAN: use-after-free in __mutex_waiter_is_first kernel/locking/mutex.c:199 [inline]
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:694 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0x1861/0x1b90 kernel/locking/mutex.c:776
Read of size 8 at addr ffff8880792800a8 by task khidpd_04f55508/20178

CPU: 0 UID: 0 PID: 20178 Comm: khidpd_04f55508 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595
 __mutex_waiter_is_first kernel/locking/mutex.c:199 [inline]
 __mutex_lock_common kernel/locking/mutex.c:694 [inline]
 __mutex_lock+0x1861/0x1b90 kernel/locking/mutex.c:776
 l2cap_unregister_user+0x71/0x240 net/bluetooth/l2cap_core.c:1721
 hidp_session_thread+0x459/0x680 net/bluetooth/hidp/core.c:1304
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888079283a80 pfn:0x79280
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00016ff708 ffff8880b8441000 0000000000000000
raw: ffff888079283a80 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 19191, tgid 19191 (syz-executor), ts 1087642703108, free_ts 1490461087917
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5250
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2484
 ___kmalloc_large_node+0x104/0x150 mm/slub.c:5201
 __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:5232
 __do_kmalloc_node mm/slub.c:5248 [inline]
 __kmalloc_noprof+0x5be/0x850 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 hci_alloc_dev_priv+0x1d/0x28a0 net/bluetooth/hci_core.c:2449
 hci_alloc_dev include/net/bluetooth/hci_core.h:1763 [inline]
 __vhci_create_device+0xf0/0x880 drivers/bluetooth/hci_vhci.c:421
 vhci_create_device drivers/bluetooth/hci_vhci.c:479 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:536 [inline]
 vhci_write+0x2c4/0x490 drivers/bluetooth/hci_vhci.c:616
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1070 fs/read_write.c:688
 ksys_write+0x12a/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 24178 tgid 24178 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x7e1/0x10d0 mm/page_alloc.c:2978
 hci_release_dev+0x4ef/0x630 net/bluetooth/hci_core.c:2777
 bt_host_release+0x6a/0xb0 net/bluetooth/hci_sysfs.c:87
 device_release+0xa4/0x240 drivers/base/core.c:2565
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1f7/0x640 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3797
 vhci_release+0x185/0x230 drivers/bluetooth/hci_vhci.c:691
 __fput+0x3ff/0xb40 fs/file_table.c:469
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x8b8/0x2b60 kernel/exit.c:976
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1118
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:98 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0x1f8/0x670 kernel/entry/common.c:219
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

Memory state around the buggy address:
 ffff88807927ff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888079280000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888079280080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                  ^
 ffff888079280100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888079280180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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