syzbot

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BUG: KASAN: use-after-free in __mutex_waiter_is_first kernel/locking/mutex.c:197 [inline]
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:681 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0x56e/0xaf0 kernel/locking/mutex.c:747
Read of size 8 at addr ffff88805c288060 by task khidpd_10000008/6560

CPU: 0 PID: 6560 Comm: khidpd_10000008 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 __mutex_waiter_is_first kernel/locking/mutex.c:197 [inline]
 __mutex_lock_common kernel/locking/mutex.c:681 [inline]
 __mutex_lock+0x56e/0xaf0 kernel/locking/mutex.c:747
 l2cap_unregister_user+0x66/0x1a0 net/bluetooth/l2cap_core.c:1895
 hidp_session_thread+0x3c4/0x400 net/bluetooth/hidp/core.c:1305
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

The buggy address belongs to the physical page:
page:ffffea000170a200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5c288
head:ffffea000170a200 order:2 compound_mapcount:0 compound_pincount:0
memcg:ffff8880281f8001
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888017442dc0
raw: 0000000000000000 0000000080100010 00000001ffffffff ffff8880281f8001
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 3627, tgid 3627 (klogd), ts 321763246826, free_ts 321630819515
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 alloc_slab_page+0x5d/0x160 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1997
 ___slab_alloc+0xbc6/0x1230 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc_node_track_caller+0x9e/0x230 mm/slab_common.c:956
 kmalloc_reserve net/core/skbuff.c:446 [inline]
 __alloc_skb+0x22a/0x7e0 net/core/skbuff.c:515
 alloc_skb include/linux/skbuff.h:1271 [inline]
 alloc_skb_with_frags+0xa7/0x710 net/core/skbuff.c:6162
 sock_alloc_send_pskb+0x853/0x980 net/core/sock.c:2755
 unix_dgram_sendmsg+0x592/0x16c0 net/unix/af_unix.c:1945
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 __sys_sendto+0x44f/0x5c0 net/socket.c:2153
 __do_sys_sendto net/socket.c:2165 [inline]
 __se_sys_sendto net/socket.c:2161 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2161
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3479
 free_large_kmalloc+0xfd/0x190 mm/slab_common.c:913
 bt_host_release+0x7e/0x90 net/bluetooth/hci_sysfs.c:85
 device_release+0x92/0x1c0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:681 [inline]
 kobject_release lib/kobject.c:712 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x21d/0x460 lib/kobject.c:729
 vhci_release+0x87/0xd0 drivers/bluetooth/hci_vhci.c:574
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x93e/0x2400 kernel/exit.c:880
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 get_signal+0x1272/0x1350 kernel/signal.c:2871
 arch_do_signal_or_restart+0xb7/0x1240 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:316

Memory state around the buggy address:
 ffff88805c287f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805c287f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805c288000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88805c288080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805c288100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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