================================================================== 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 ffff88801eff1af8 by task syz-executor/5830 CPU: 1 UID: 0 PID: 5830 Comm: syz-executor 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: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_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2b7/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0e80d5b78e Code: Unable to access opcode bytes at 0x7f0e80d5b764. RSP: 002b:00007fff5cee0d08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: fffffffffffffe00 RBX: 0000555584218500 RCX: 00007f0e80d5b78e RDX: 0000000000000030 RSI: 00007fff5cee0e00 RDI: 00000000000000f9 RBP: 00007fff5cee0dac R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000259 R13: 00000000000927c0 R14: 00000000000a0618 R15: 00007fff5cee0e00 Allocated by task 13838: 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 copy_tree+0x3d4/0x930 fs/namespace.c:2194 copy_mnt_ns+0x24d/0x990 fs/namespace.c:4246 create_new_namespaces+0xcf/0x6a0 kernel/nsproxy.c:98 unshare_nsproxy_namespaces+0x11a/0x160 kernel/nsproxy.c:226 ksys_unshare+0x4f4/0x900 kernel/fork.c:3173 __do_sys_unshare kernel/fork.c:3244 [inline] __se_sys_unshare kernel/fork.c:3242 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3242 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 1037: 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+0x180/0x610 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/0x7c0 kernel/softirq.c:626 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] __alloc_skb+0x1aa/0x7d0 net/core/skbuff.c:696 alloc_skb include/linux/skbuff.h:1383 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline] nsim_dev_trap_report_work+0x29a/0xb80 drivers/net/netdevsim/dev.c:922 process_one_work+0x949/0x15a0 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+0x51b/0xa40 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_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2b7/0xf80 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 mntput fs/namespace.c:1416 [inline] namespace_unlock+0x704/0x7a0 fs/namespace.c:1713 do_umount fs/namespace.c:1952 [inline] path_umount+0xae4/0xb40 fs/namespace.c:2032 ksys_umount fs/namespace.c:2055 [inline] __do_sys_umount fs/namespace.c:2060 [inline] __se_sys_umount fs/namespace.c:2058 [inline] __x64_sys_umount+0x12a/0x170 fs/namespace.c:2058 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88801eff1a40 which belongs to the cache mnt_cache of size 352 The buggy address is located 184 bytes inside of freed 352-byte region [ffff88801eff1a40, ffff88801eff1ba0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88801eff1180 pfn:0x1eff0 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff888033b93b01 flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000240 ffff888140412640 ffffea0001a50a90 ffffea000070a690 raw: ffff88801eff1180 000000080012000f 00000000f5000000 ffff888033b93b01 head: 00fff00000000240 ffff888140412640 ffffea0001a50a90 ffffea000070a690 head: ffff88801eff1180 000000080012000f 00000000f5000000 ffff888033b93b01 head: 00fff00000000001 ffffea00007bfc01 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 5822, tgid 5822 (syz-executor), ts 80885787535, free_ts 80883995916 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 clone_mnt+0x4b/0x9a0 fs/namespace.c:1246 copy_tree+0x3d4/0x930 fs/namespace.c:2194 do_loopback+0x386/0x6c0 fs/namespace.c:3006 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+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5489 tgid 5489 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 mm_free_pgd kernel/fork.c:585 [inline] __mmdrop+0xb5/0x750 kernel/fork.c:727 mmdrop include/linux/sched/mm.h:55 [inline] mmdrop_sched include/linux/sched/mm.h:83 [inline] mmdrop_lazy_tlb_sched include/linux/sched/mm.h:110 [inline] finish_task_switch+0x449/0x920 kernel/sched/core.c:5177 context_switch kernel/sched/core.c:5298 [inline] __schedule+0x1541/0x5080 kernel/sched/core.c:6907 __schedule_loop kernel/sched/core.c:6989 [inline] schedule+0x164/0x360 kernel/sched/core.c:7004 schedule_hrtimeout_range_clock+0x1e7/0x320 kernel/time/sleep_timeout.c:207 poll_schedule_timeout+0xd0/0x1a0 fs/select.c:241 do_poll fs/select.c:954 [inline] do_sys_poll+0x7e8/0x1120 fs/select.c:1005 __do_sys_ppoll fs/select.c:1107 [inline] __se_sys_ppoll+0x209/0x2b0 fs/select.c:1087 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88801eff1980: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88801eff1a00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff88801eff1a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801eff1b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801eff1b80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================