================================================================== BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75 Read of size 8 at addr ffff8881321a7590 by task syz.0.3140/11517 CPU: 0 PID: 11517 Comm: syz.0.3140 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x71/0x200 mm/kasan/report.c:316 print_report+0x4a/0x60 mm/kasan/report.c:420 kasan_report+0x122/0x150 mm/kasan/report.c:524 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351 rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75 rcu_do_batch+0x4bc/0xc30 kernel/rcu/tree.c:2285 rcu_core+0x486/0xf00 kernel/rcu/tree.c:2557 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574 handle_softirqs+0x1dd/0x5f0 kernel/softirq.c:642 __do_softirq kernel/softirq.c:680 [inline] invoke_softirq kernel/softirq.c:497 [inline] __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:729 irq_exit_rcu+0x9/0x10 kernel/softirq.c:741 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0x58/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0033:0x7fc506c73f5a Code: 48 8b 1c 24 49 8b 54 24 40 4c 89 f0 4a 03 14 eb 80 3d 61 3e 3b 00 00 49 89 d6 48 89 d3 74 28 25 ff 0f 00 00 83 f0 3d 8d 04 c0 <89> c3 c1 eb 04 31 c3 69 db 2d eb d4 27 89 d8 c1 e8 0f 31 c3 81 e3 RSP: 002b:00007ffc576344a0 EFLAGS: 00000202 RAX: 0000000000003069 RBX: ffffffff817465c0 RCX: ffffffff817462e5 RDX: ffffffff817465c0 RSI: ffffffff817462e5 RDI: 0000000000000010 RBP: 00000000000001cf R08: 00007fc507010000 R09: 00007fc507012000 R10: 00000000817462e9 R11: 0000000000000010 R12: 00007fc507026038 R13: 000000000007d07b R14: ffffffff817465c0 R15: 00007fc507b55720 Allocated by task 11531: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:380 [inline] __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389 kasan_kmalloc include/linux/kasan.h:212 [inline] __do_kmalloc_node mm/slab_common.c:938 [inline] __kmalloc+0xb4/0x1e0 mm/slab_common.c:951 kmalloc include/linux/slab.h:568 [inline] kzalloc include/linux/slab.h:699 [inline] l2tp_session_create+0x38/0xbd0 net/l2tp/l2tp_core.c:1614 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771 __sys_connect_file net/socket.c:2001 [inline] __sys_connect+0x3da/0x460 net/socket.c:2018 __do_sys_connect net/socket.c:2028 [inline] __se_sys_connect net/socket.c:2025 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2025 x64_sys_call+0x88d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Freed by task 3137: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250 kasan_slab_free include/linux/kasan.h:178 [inline] slab_free_hook mm/slub.c:1750 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776 slab_free mm/slub.c:3712 [inline] __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728 kfree+0x6f/0xf0 mm/slab_common.c:990 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline] l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193 l2tp_session_delete+0x3df/0x4d0 net/l2tp/l2tp_core.c:1587 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1233 [inline] l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1271 process_one_work+0x717/0xc30 kernel/workqueue.c:2302 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449 kthread+0x281/0x320 kernel/kthread.c:386 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496 __call_rcu_common kernel/rcu/tree.c:2807 [inline] call_rcu+0xcf/0xf50 kernel/rcu/tree.c:2926 pppol2tp_release+0x1e3/0x2b0 net/l2tp/l2tp_ppp.c:446 __sock_release net/socket.c:652 [inline] sock_close+0xc9/0x220 net/socket.c:1390 __fput+0x1fd/0x8f0 fs/file_table.c:320 ____fput+0x15/0x20 fs/file_table.c:348 task_work_run+0x1e1/0x250 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Second to last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496 __call_rcu_common kernel/rcu/tree.c:2807 [inline] call_rcu+0xcf/0xf50 kernel/rcu/tree.c:2926 __qdisc_destroy+0x187/0x290 net/sched/sch_generic.c:1083 qdisc_put net/sched/sch_generic.c:1103 [inline] dev_shutdown+0x459/0x580 net/sched/sch_generic.c:1464 unregister_netdevice_many+0x9a0/0x1910 net/core/dev.c:10997 xfrmi_exit_batch_net+0x26d/0x2c0 net/xfrm/xfrm_interface_core.c:968 ops_exit_list net/core/net_namespace.c:177 [inline] cleanup_net+0x630/0xb10 net/core/net_namespace.c:604 process_one_work+0x717/0xc30 kernel/workqueue.c:2302 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449 kthread+0x281/0x320 kernel/kthread.c:386 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 The buggy address belongs to the object at ffff8881321a7400 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 400 bytes inside of 512-byte region [ffff8881321a7400, ffff8881321a7600) The buggy address belongs to the physical page: page:ffffea0004c86900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1321a4 head:ffffea0004c86900 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 ffffea0004964000 dead000000000003 ffff888100042f00 raw: 0000000000000000 0000000000100010 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 290, tgid 290 (syz-executor), ts 24429033358, free_ts 0 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2673 prep_new_page+0x1c/0x110 mm/page_alloc.c:2680 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4587 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5931 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1 allocate_slab mm/slub.c:1967 [inline] new_slab+0x98/0x3e0 mm/slub.c:2020 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177 __slab_alloc+0x5e/0xa0 mm/slub.c:3263 slab_alloc_node mm/slub.c:3348 [inline] __kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423 __do_kmalloc_node mm/slab_common.c:937 [inline] __kmalloc_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958 kmalloc_reserve net/core/skbuff.c:449 [inline] __alloc_skb+0x226/0x4a0 net/core/skbuff.c:518 alloc_skb include/linux/skbuff.h:1322 [inline] nlmsg_new include/net/netlink.h:987 [inline] rtmsg_ifa+0xfa/0x1e0 net/ipv4/devinet.c:1933 __inet_insert_ifa+0x83f/0xa30 net/ipv4/devinet.c:567 inet_rtm_newaddr+0x8be/0x1650 net/ipv4/devinet.c:970 rtnetlink_rcv_msg+0xb28/0xde0 net/core/rtnetlink.c:6162 netlink_rcv_skb+0x200/0x450 net/netlink/af_netlink.c:2526 page_owner free stack trace missing Memory state around the buggy address: ffff8881321a7480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881321a7500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881321a7580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881321a7600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881321a7680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================