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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+0x812/0x1300 kernel/locking/mutex.c:776
Read of size 8 at addr ffff88804a0980a8 by task khidpd_10cf0005/12490

CPU: 0 UID: 0 PID: 12490 Comm: khidpd_10cf0005 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 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+0x812/0x1300 kernel/locking/mutex.c:776
 l2cap_unregister_user+0x6a/0x1b0 net/bluetooth/l2cap_core.c:1721
 hidp_session_thread+0x3cb/0x440 net/bluetooth/hidp/core.c:1304
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 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:0xffff88804a099380 pfn:0x4a098
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001e0ee08 ffff8880b8740c40 0000000000000000
raw: ffff88804a099380 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 0x92c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_NOMEMALLOC), pid 13539, tgid 13538 (syz.2.10574), ts 1422185381443, free_ts 1422185626827
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2485
 alloc_frozen_pages_noprof mm/mempolicy.c:2556 [inline]
 alloc_pages_noprof+0xa8/0x190 mm/mempolicy.c:2576
 stack_depot_save_flags+0x73c/0x810 lib/stackdepot.c:685
 kasan_save_stack mm/kasan/common.c:58 [inline]
 kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4501 [inline]
 slab_alloc_node mm/slub.c:4830 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4837
 new_handle fs/jbd2/transaction.c:457 [inline]
 jbd2__journal_start+0x145/0x5b0 fs/jbd2/transaction.c:484
 __ext4_journal_start_sb+0x203/0x620 fs/ext4/ext4_jbd2.c:114
 __ext4_journal_start fs/ext4/ext4_jbd2.h:242 [inline]
 ext4_evict_inode+0x5d9/0xeb0 fs/ext4/inode.c:227
 evict+0x61e/0xb10 fs/inode.c:846
 __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670
 finish_dput+0xc9/0x480 fs/dcache.c:879
 __fput+0x691/0xa70 fs/file_table.c:477
page last free pid 13539 tgid 13538 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 stack_depot_save_flags+0x40e/0x810 lib/stackdepot.c:735
 kasan_save_stack mm/kasan/common.c:58 [inline]
 kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4501 [inline]
 slab_alloc_node mm/slub.c:4830 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4837
 new_handle fs/jbd2/transaction.c:457 [inline]
 jbd2__journal_start+0x145/0x5b0 fs/jbd2/transaction.c:484
 __ext4_journal_start_sb+0x203/0x620 fs/ext4/ext4_jbd2.c:114
 __ext4_journal_start fs/ext4/ext4_jbd2.h:242 [inline]
 ext4_evict_inode+0x5d9/0xeb0 fs/ext4/inode.c:227
 evict+0x61e/0xb10 fs/inode.c:846
 __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670
 finish_dput+0xc9/0x480 fs/dcache.c:879
 __fput+0x691/0xa70 fs/file_table.c:477
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x69b/0x2320 kernel/exit.c:971
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 get_signal+0x1284/0x1330 kernel/signal.c:3034

Memory state around the buggy address:
 ffff88804a097f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804a098000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88804a098080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                  ^
 ffff88804a098100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804a098180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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