================================================================== BUG: KASAN: use-after-free in rcu_segcblist_enqueue+0x9c/0xb0 kernel/rcu/rcu_segcblist.c:348 Write of size 8 at addr ffff8881401ad990 by task kworker/u4:13/1060 CPU: 1 PID: 1060 Comm: kworker/u4:13 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: l2tp l2tp_tunnel_del_work Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report+0x10f/0x150 mm/kasan/report.c:444 __asan_report_store8_noabort+0x17/0x20 mm/kasan/report_generic.c:314 rcu_segcblist_enqueue+0x9c/0xb0 kernel/rcu/rcu_segcblist.c:348 __call_rcu_common kernel/rcu/tree.c:3030 [inline] call_rcu+0x549/0xf60 kernel/rcu/tree.c:3129 radix_tree_node_free lib/radix-tree.c:308 [inline] delete_node+0x1c0/0xa60 lib/radix-tree.c:571 __radix_tree_delete+0x258/0x3c0 lib/radix-tree.c:1377 radix_tree_delete_item+0x2fc/0x410 lib/radix-tree.c:1428 idr_remove+0x43/0x60 lib/idr.c:156 l2tp_tunnel_remove net/l2tp/l2tp_core.c:1263 [inline] l2tp_tunnel_del_work+0x34f/0x3d0 net/l2tp/l2tp_core.c:1287 process_one_work+0x6c8/0xbb0 kernel/workqueue.c:2328 worker_thread+0xaa0/0x1250 kernel/workqueue.c:2475 kthread+0x3f5/0x4f0 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Allocated by task 9663: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:433 [inline] ____kasan_kmalloc mm/kasan/common.c:512 [inline] __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:521 kasan_kmalloc include/linux/kasan.h:227 [inline] __kmalloc+0x13d/0x2c0 mm/slub.c:4436 kmalloc include/linux/slab.h:624 [inline] kzalloc include/linux/slab.h:750 [inline] l2tp_session_create+0x39/0xb60 net/l2tp/l2tp_core.c:1616 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:772 __sys_connect_file net/socket.c:1922 [inline] __sys_connect+0x3cb/0x450 net/socket.c:1939 __do_sys_connect net/socket.c:1949 [inline] __se_sys_connect net/socket.c:1946 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:1946 x64_sys_call+0x7c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Freed by task 1060: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754 slab_free mm/slub.c:3526 [inline] kfree+0xc4/0x270 mm/slub.c:4588 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline] l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193 l2tp_session_delete+0x3a9/0x4a0 net/l2tp/l2tp_core.c:1589 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1235 [inline] l2tp_tunnel_del_work+0x180/0x3d0 net/l2tp/l2tp_core.c:1273 process_one_work+0x6c8/0xbb0 kernel/workqueue.c:2328 worker_thread+0xaa0/0x1250 kernel/workqueue.c:2475 kthread+0x3f5/0x4f0 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 __call_rcu_common kernel/rcu/tree.c:3011 [inline] call_rcu+0x10b/0xf60 kernel/rcu/tree.c:3129 pppol2tp_release+0x1e3/0x2b0 net/l2tp/l2tp_ppp.c:447 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x200 net/socket.c:1335 __fput+0x22b/0x900 fs/file_table.c:311 ____fput+0x15/0x20 fs/file_table.c:339 task_work_run+0x127/0x190 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0xd0/0xe0 kernel/entry/common.c:181 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 The buggy address belongs to the object at ffff8881401ad800 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 400 bytes inside of 512-byte region [ffff8881401ad800, ffff8881401ada00) The buggy address belongs to the page: page:ffffea0005006b00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1401ac head:ffffea0005006b00 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 0000000100000001 ffff888100042f00 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 9587, ts 387675901771, free_ts 316678866610 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607 prep_new_page+0x1c/0x110 mm/page_alloc.c:2613 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1937 [inline] new_slab+0xa0/0x4d0 mm/slub.c:2000 ___slab_alloc+0x3ac/0x840 mm/slub.c:3033 __slab_alloc+0x49/0x90 mm/slub.c:3120 slab_alloc_node mm/slub.c:3211 [inline] slab_alloc mm/slub.c:3255 [inline] __kmalloc_track_caller+0x169/0x2c0 mm/slub.c:4954 kmalloc_reserve net/core/skbuff.c:357 [inline] pskb_expand_head+0x123/0x1280 net/core/skbuff.c:1734 skb_ensure_writable+0x2e0/0x460 net/core/skbuff.c:5824 __bpf_try_make_writable net/core/filter.c:1667 [inline] bpf_try_make_writable net/core/filter.c:1673 [inline] bpf_try_make_head_writable net/core/filter.c:1681 [inline] ____bpf_clone_redirect net/core/filter.c:2456 [inline] bpf_clone_redirect+0x1c6/0x460 net/core/filter.c:2425 0xffffffffa002c63e bpf_dispatcher_nop_func include/linux/bpf.h:785 [inline] __bpf_prog_run include/linux/filter.h:628 [inline] bpf_prog_run include/linux/filter.h:635 [inline] bpf_test_run+0x351/0x900 net/bpf/test_run.c:119 bpf_prog_test_run_skb+0xa09/0x11d0 net/bpf/test_run.c:674 bpf_prog_test_run+0x3a5/0x5b0 kernel/bpf/syscall.c:3348 __sys_bpf+0x590/0x7d0 kernel/bpf/syscall.c:4651 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1474 [inline] free_pcp_prepare mm/page_alloc.c:1546 [inline] free_unref_page_prepare+0x5fa/0x600 mm/page_alloc.c:3536 free_unref_page+0xae/0x540 mm/page_alloc.c:3618 free_the_page mm/page_alloc.c:805 [inline] __free_pages+0x6c/0x100 mm/page_alloc.c:5900 __vunmap+0x801/0x980 mm/vmalloc.c:2660 __vfree mm/vmalloc.c:2709 [inline] vfree+0x8b/0xc0 mm/vmalloc.c:2740 free_pg_vec net/packet/af_packet.c:4342 [inline] packet_set_ring+0x18dc/0x2480 net/packet/af_packet.c:4563 packet_release+0x76b/0xd00 net/packet/af_packet.c:3166 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x200 net/socket.c:1335 __fput+0x22b/0x900 fs/file_table.c:311 ____fput+0x15/0x20 fs/file_table.c:339 task_work_run+0x127/0x190 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xb70/0x29a0 kernel/exit.c:890 do_group_exit+0x149/0x310 kernel/exit.c:1004 get_signal+0x64f/0x1430 kernel/signal.c:2907 arch_do_signal_or_restart+0xe2/0x1100 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0xa7/0xe0 kernel/entry/common.c:178 Memory state around the buggy address: ffff8881401ad880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881401ad900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881401ad980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881401ada00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881401ada80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================