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BUG: KASAN: slab-use-after-free in __list_del_entry_valid_or_report+0x92/0x190 lib/list_debug.c:62
Read of size 8 at addr ffff888033cf15b8 by task syz.4.11439/1963

CPU: 1 UID: 0 PID: 1963 Comm: syz.4.11439 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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
 __list_del_entry_valid_or_report+0x92/0x190 lib/list_debug.c:62
 __list_del_entry_valid include/linux/list.h:132 [inline]
 __list_del_entry include/linux/list.h:223 [inline]
 list_del_init include/linux/list.h:295 [inline]
 trace_transfers fs/pnode.c:132 [inline]
 bulk_make_private+0xd9/0x8b0 fs/pnode.c:168
 umount_tree+0x582/0xd90 fs/namespace.c:1786
 put_mnt_ns+0x1d6/0x2f0 fs/namespace.c:6230
 nsproxy_free kernel/nsproxy.c:65 [inline]
 deactivate_nsproxy+0x41/0x140 kernel/nsproxy.c:79
 do_exit+0x696/0x2310 kernel/exit.c:970
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 get_signal+0x1284/0x1330 kernel/signal.c:3034
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe0d715b78e
Code: Unable to access opcode bytes at 0x7fe0d715b764.
RSP: 002b:00007fe0d80c9f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007fe0d80ca6c0 RCX: 00007fe0d715b78e
RDX: 00007fe0d80c9fb0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe0d7208c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe0d7416038 R14: 00007fe0d7415fa0 R15: 00007fffaf38b548
 </TASK>

Allocated by task 3808:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/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:4456 [inline]
 slab_alloc_node mm/slub.c:4785 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4792
 alloc_vfsmnt+0x23/0x420 fs/namespace.c:287
 clone_mnt+0x4b/0x9a0 fs/namespace.c:1246
 create_new_namespace fs/namespace.c:3098 [inline]
 open_new_namespace fs/namespace.c:3168 [inline]
 vfs_open_tree+0x507/0x1040 fs/namespace.c:3217
 __do_sys_open_tree fs/namespace.c:3227 [inline]
 __se_sys_open_tree fs/namespace.c:3225 [inline]
 __x64_sys_open_tree+0x96/0x110 fs/namespace.c:3225
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 3808:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2667 [inline]
 slab_free mm/slub.c:6079 [inline]
 kmem_cache_free+0x187/0x630 mm/slub.c:6205
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
 handle_softirqs+0x22a/0x870 kernel/softirq.c:626
 __do_softirq kernel/softirq.c:660 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:727
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:743
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3131 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3251
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 task_work_add+0xb6/0x440 kernel/task_work.c:70
 mntput_no_expire_slowpath+0x70c/0xbd0 fs/namespace.c:1379
 create_new_namespace fs/namespace.c:3162 [inline]
 open_new_namespace fs/namespace.c:3168 [inline]
 vfs_open_tree+0xe17/0x1040 fs/namespace.c:3217
 __do_sys_open_tree fs/namespace.c:3227 [inline]
 __se_sys_open_tree fs/namespace.c:3225 [inline]
 __x64_sys_open_tree+0x96/0x110 fs/namespace.c:3225
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888033cf1500
 which belongs to the cache mnt_cache of size 352
The buggy address is located 184 bytes inside of
 freed 352-byte region [ffff888033cf1500, ffff888033cf1660)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33cf0
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888035fe0501
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff888140412640 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800120012 00000000f5000000 ffff888035fe0501
head: 00fff00000000040 ffff888140412640 dead000000000100 dead000000000122
head: 0000000000000000 0000000800120012 00000000f5000000 ffff888035fe0501
head: 00fff00000000001 ffffea0000cf3c01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5158, tgid 5158 (mount), ts 33903070920, free_ts 27171404554
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1883
 prep_new_page mm/page_alloc.c:1891 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3956
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5244
 alloc_slab_page mm/slub.c:3235 [inline]
 allocate_slab+0x7b/0x660 mm/slub.c:3408
 new_slab mm/slub.c:3466 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7084
 refill_sheaf mm/slub.c:2784 [inline]
 __pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4533
 alloc_from_pcs mm/slub.c:4636 [inline]
 slab_alloc_node mm/slub.c:4770 [inline]
 kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4792
 alloc_vfsmnt+0x23/0x420 fs/namespace.c:287
 vfs_create_mount+0x69/0x320 fs/namespace.c:1178
 fc_mount fs/namespace.c:1196 [inline]
 do_new_mount_fc fs/namespace.c:3760 [inline]
 do_new_mount+0x3bf/0xd30 fs/namespace.c:3836
 do_mount fs/namespace.c:4159 [inline]
 __do_sys_mount fs/namespace.c:4348 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4325
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 42 tgid 42 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1432 [inline]
 __free_frozen_pages+0xc01/0xd80 mm/page_alloc.c:2972
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3398
 process_one_work+0x949/0x1650 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0xb46/0x1140 kernel/workqueue.c:3443
 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

Memory state around the buggy address:
 ffff888033cf1480: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888033cf1500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888033cf1580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff888033cf1600: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888033cf1680: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
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