==================================================================
BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x105/0x130 lib/list_debug.c:29
Read of size 8 at addr ffff888070c62980 by task syz.0.1842/10320

CPU: 1 UID: 0 PID: 10320 Comm: syz.0.1842 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 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
 __list_add_valid_or_report+0x105/0x130 lib/list_debug.c:29
 __list_add_valid include/linux/list.h:96 [inline]
 __list_add include/linux/list.h:158 [inline]
 list_add include/linux/list.h:177 [inline]
 clone_mnt+0x633/0x930 fs/namespace.c:1275
 create_new_namespace fs/namespace.c:3098 [inline]
 open_new_namespace fs/namespace.c:3168 [inline]
 vfs_open_tree+0xb02/0x1500 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+0xa3/0x150 fs/namespace.c:3225
 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
RIP: 0033:0x7f6658f9bf79
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6659f32028 EFLAGS: 00000246 ORIG_RAX: 00000000000001ac
RAX: ffffffffffffffda RBX: 00007f6659215fa0 RCX: 00007f6658f9bf79
RDX: 0000000000009902 RSI: 0000200000000640 RDI: ffffffffffffff9c
RBP: 00007f66590327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6659216038 R14: 00007f6659215fa0 R15: 00007ffd8114e9d8
 </TASK>

Allocated by task 10165:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4459 [inline]
 slab_alloc_node mm/slub.c:4788 [inline]
 kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4795
 alloc_vfsmnt+0x23/0x6a0 fs/namespace.c:287
 clone_mnt+0x4b/0x930 fs/namespace.c:1246
 create_new_namespace fs/namespace.c:3098 [inline]
 open_new_namespace fs/namespace.c:3168 [inline]
 vfs_open_tree+0xb02/0x1500 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+0xa3/0x150 fs/namespace.c:3225
 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

Freed by task 10121:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2670 [inline]
 slab_free mm/slub.c:6082 [inline]
 kmem_cache_free+0x124/0x6a0 mm/slub.c:6212
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x5a2/0x10d0 kernel/rcu/tree.c:2869
 handle_softirqs+0x1eb/0x9e0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xef/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 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+0x30/0x50 mm/kasan/common.c:57
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 __call_rcu_common.constprop.0+0xa5/0x9b0 kernel/rcu/tree.c:3131
 task_work_run+0x150/0x240 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+0x100/0x4a0 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+0x67c/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+0x30/0x50 mm/kasan/common.c:57
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 task_work_add+0x28b/0x3b0 kernel/task_work.c:70
 mntput_no_expire_slowpath+0x3da/0xb00 fs/namespace.c:1379
 mntput_no_expire+0x1fd/0x220 fs/namespace.c:1406
 mntput+0x6b/0xa0 fs/namespace.c:1416
 create_new_namespace fs/namespace.c:3082 [inline]
 open_new_namespace fs/namespace.c:3168 [inline]
 vfs_open_tree+0x1235/0x1500 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+0xa3/0x150 fs/namespace.c:3225
 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

The buggy address belongs to the object at ffff888070c628c0
 which belongs to the cache mnt_cache of size 352
The buggy address is located 192 bytes inside of
 freed 352-byte region [ffff888070c628c0, ffff888070c62a20)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888070c62c40 pfn:0x70c62
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88802d07f901
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff888140416140 ffffea00007cbb10 ffffea000073b110
raw: ffff888070c62c40 0000000800120007 00000000f5000000 ffff88802d07f901
head: 00fff00000000240 ffff888140416140 ffffea00007cbb10 ffffea000073b110
head: ffff888070c62c40 0000000800120007 00000000f5000000 ffff88802d07f901
head: 00fff00000000001 ffffea0001c31881 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 5806, tgid 5806 (syz-executor), ts 55113712120, free_ts 13078365602
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1888
 prep_new_page mm/page_alloc.c:1896 [inline]
 get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3961
 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5249
 alloc_slab_page mm/slub.c:3238 [inline]
 allocate_slab mm/slub.c:3411 [inline]
 new_slab+0xa6/0x6e0 mm/slub.c:3469
 refill_objects+0x26b/0x400 mm/slub.c:7091
 refill_sheaf mm/slub.c:2787 [inline]
 alloc_full_sheaf mm/slub.c:2808 [inline]
 __pcs_replace_empty_main+0x19f/0x600 mm/slub.c:4546
 alloc_from_pcs mm/slub.c:4639 [inline]
 slab_alloc_node mm/slub.c:4773 [inline]
 kmem_cache_alloc_noprof+0x480/0x6e0 mm/slub.c:4795
 alloc_vfsmnt+0x23/0x6a0 fs/namespace.c:287
 clone_mnt+0x4b/0x930 fs/namespace.c:1246
 copy_tree+0x329/0xbf0 fs/namespace.c:2194
 copy_mnt_ns+0x2bd/0xc30 fs/namespace.c:4246
 create_new_namespaces+0xd3/0xac0 kernel/nsproxy.c:98
 unshare_nsproxy_namespaces+0xc3/0x1f0 kernel/nsproxy.c:226
 ksys_unshare+0x455/0xab0 kernel/fork.c:3174
 __do_sys_unshare kernel/fork.c:3245 [inline]
 __se_sys_unshare kernel/fork.c:3243 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:3243
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1432 [inline]
 __free_frozen_pages+0x7ca/0x10a0 mm/page_alloc.c:2977
 __free_pages mm/page_alloc.c:5368 [inline]
 free_contig_range+0xde/0x1d0 mm/page_alloc.c:7372
 debug_vm_pgtable_free_huge_page mm/debug_vm_pgtable.c:980 [inline]
 destroy_args+0xa8/0x7a0 mm/debug_vm_pgtable.c:993
 debug_vm_pgtable+0x1b66/0x34c0 mm/debug_vm_pgtable.c:1368
 do_one_initcall+0x11d/0x760 init/main.c:1382
 do_initcall_level init/main.c:1444 [inline]
 do_initcalls init/main.c:1460 [inline]
 do_basic_setup init/main.c:1479 [inline]
 kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
 kernel_init+0x1f/0x1e0 init/main.c:1582
 ret_from_fork+0x754/0xd80 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:
 ffff888070c62880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
 ffff888070c62900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888070c62980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888070c62a00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888070c62a80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Call Trace:
 __do_sys_open_tree fs/namespace.c:3227 [inline]
 __se_sys_open_tree fs/namespace.c:3225 [inline]
 __x64_sys_open_tree+0xa3/0x150 fs/namespace.c:3225
 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
RIP: 0033:0x7f6658f9bf79
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6659f32028 EFLAGS: 00000246 ORIG_RAX: 00000000000001ac
RAX: ffffffffffffffda RBX: 00007f6659215fa0 RCX: 00007f6658f9bf79
RDX: 0000000000009902 RSI: 0000200000000640 RDI: ffffffffffffff9c
RBP: 00007f66590327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6659216038 R14: 00007f6659215fa0 R15: 00007ffd8114e9d8
 </TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..