================================================================== 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 ffff88807a1c20b8 by task syz.7.6306/418 CPU: 0 UID: 0 PID: 418 Comm: syz.7.6306 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: 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:6240 nsproxy_free kernel/nsproxy.c:65 [inline] deactivate_nsproxy+0x41/0x140 kernel/nsproxy.c:79 do_exit+0x696/0x2320 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 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+0x176/0x620 kernel/entry/common.c:219 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0033:0x7fa799d9bf81 Code: Unable to access opcode bytes at 0x7fa799d9bf57. RSP: 002b:0000000000000020 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007fa79a015fa0 RCX: 00007fa799d9bf79 RDX: 0000000000000000 RSI: 0000000000000020 RDI: 0000000024862080 RBP: 00007fa799e327e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007fa79a016038 R14: 00007fa79a015fa0 R15: 00007ffc48ff33e8 Allocated by task 423: 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:4501 [inline] slab_alloc_node mm/slub.c:4830 [inline] kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4837 alloc_vfsmnt+0x23/0x420 fs/namespace.c:287 clone_mnt+0x4b/0x9a0 fs/namespace.c:1246 create_new_namespace fs/namespace.c:3093 [inline] open_new_namespace+0x22f/0xd60 fs/namespace.c:3168 vfs_open_tree+0x331/0x3d0 fs/namespace.c:3217 __do_sys_open_tree fs/namespace.c:3229 [inline] __se_sys_open_tree fs/namespace.c:3227 [inline] __x64_sys_open_tree+0x96/0x110 fs/namespace.c:3227 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 23: 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:2687 [inline] slab_free mm/slub.c:6124 [inline] kmem_cache_free+0x187/0x630 mm/slub.c:6254 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 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1067 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 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 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:3161 [inline] open_new_namespace+0x262/0xd60 fs/namespace.c:3168 vfs_open_tree+0x331/0x3d0 fs/namespace.c:3217 __do_sys_open_tree fs/namespace.c:3229 [inline] __se_sys_open_tree fs/namespace.c:3227 [inline] __x64_sys_open_tree+0x96/0x110 fs/namespace.c:3227 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 ffff88807a1c2000 which belongs to the cache mnt_cache of size 352 The buggy address is located 184 bytes inside of freed 352-byte region [ffff88807a1c2000, ffff88807a1c2160) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88807a1c2540 pfn:0x7a1c2 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff88807a1c2171 flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000240 ffff88801c2f5640 ffffea0001d76a90 ffffea00009e3a10 raw: ffff88807a1c2540 000001c000120009 00000000f5000000 ffff88807a1c2171 head: 00fff00000000240 ffff88801c2f5640 ffffea0001d76a90 ffffea00009e3a10 head: ffff88807a1c2540 000001c000120009 00000000f5000000 ffff88807a1c2171 head: 00fff00000000001 ffffea0001e87081 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 26804, tgid 26802 (syz.1.4693), ts 554475650218, free_ts 554374140898 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_slab_page mm/slub.c:3255 [inline] allocate_slab+0x77/0x660 mm/slub.c:3444 new_slab mm/slub.c:3502 [inline] refill_objects+0x331/0x3c0 mm/slub.c:7134 refill_sheaf mm/slub.c:2804 [inline] __pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4578 alloc_from_pcs mm/slub.c:4681 [inline] slab_alloc_node mm/slub.c:4815 [inline] kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4837 alloc_vfsmnt+0x23/0x420 fs/namespace.c:287 clone_mnt+0x4b/0x9a0 fs/namespace.c:1246 copy_tree+0x3d4/0x930 fs/namespace.c:2194 copy_mnt_ns+0x24d/0x990 fs/namespace.c:4248 create_new_namespaces+0xcf/0x6a0 kernel/nsproxy.c:98 copy_namespaces+0x438/0x4b0 kernel/nsproxy.c:195 copy_process+0x18e2/0x3cf0 kernel/fork.c:2226 kernel_clone+0x248/0x8e0 kernel/fork.c:2654 __do_sys_clone kernel/fork.c:2795 [inline] __se_sys_clone kernel/fork.c:2779 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2779 page last free pid 26799 tgid 26799 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 __slab_free+0x263/0x2b0 mm/slub.c:5532 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 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] __do_kmalloc_node mm/slub.c:5218 [inline] __kmalloc_noprof+0x316/0x760 mm/slub.c:5231 kmalloc_noprof include/linux/slab.h:966 [inline] kzalloc_noprof include/linux/slab.h:1204 [inline] tomoyo_encode2 security/tomoyo/realpath.c:45 [inline] tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80 tomoyo_path_perm+0x318/0x560 security/tomoyo/file.c:836 tomoyo_path_symlink+0xab/0xf0 security/tomoyo/tomoyo.c:212 security_path_symlink+0x16f/0x360 security/security.c:1476 filename_symlinkat+0x134/0x410 fs/namei.c:5638 __do_sys_symlinkat fs/namei.c:5660 [inline] __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5655 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 Memory state around the buggy address: ffff88807a1c1f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88807a1c2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88807a1c2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807a1c2100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88807a1c2180: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ==================================================================