================================================================== BUG: KASAN: use-after-free in rcu_segcblist_enqueue+0x62/0xb0 kernel/rcu/rcu_segcblist.c:345 Write of size 8 at addr ffff888120f97590 by task syz.4.83/528 CPU: 1 PID: 528 Comm: syz.4.83 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/08/2026 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_store8_noabort+0x17/0x20 mm/kasan/report_generic.c:356 rcu_segcblist_enqueue+0x62/0xb0 kernel/rcu/rcu_segcblist.c:345 __call_rcu_common kernel/rcu/tree.c:2827 [inline] call_rcu+0x554/0xf50 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 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0xb03/0x2970 kernel/exit.c:894 __do_sys_exit kernel/exit.c:1004 [inline] __se_sys_exit kernel/exit.c:1002 [inline] __x64_sys_exit+0x40/0x40 kernel/exit.c:1002 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61 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 RIP: 0033:0x7f561779e159 Code: Unable to access opcode bytes at 0x7f561779e12f. RSP: 002b:00007f5618584ef8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f561779e159 RDX: 00007f56185859c8 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f561783506b R08: 0000000000000000 R09: 0000000000000058 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5617a26038 R14: 00007f5617a25fa0 R15: 00007fff14de2ad8 Allocated by task 527: 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 10: 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 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0xb03/0x2970 kernel/exit.c:894 __do_sys_exit kernel/exit.c:1004 [inline] __se_sys_exit kernel/exit.c:1002 [inline] __cfi___ia32_sys_exit+0x0/0x10 kernel/exit.c:1002 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61 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 The buggy address belongs to the object at ffff888120f97400 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 400 bytes inside of 512-byte region [ffff888120f97400, ffff888120f97600) The buggy address belongs to the physical page: page:ffffea000483e500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x120f94 head:ffffea000483e500 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 dead000000000122 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 515, tgid 515 (syz.4.77), ts 29840406816, free_ts 29795316024 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 kmalloc_trace+0x29/0xb0 mm/slab_common.c:1028 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] kvm_set_memslot+0x92/0x1160 virt/kvm/kvm_main.c:1860 __kvm_set_memory_region+0x52d/0x8c0 virt/kvm/kvm_main.c:1990 __x86_set_memory_region+0x3f4/0x4d0 arch/x86/kvm/x86.c:12675 kvm_arch_destroy_vm+0xdc/0x3f0 arch/x86/kvm/x86.c:12701 kvm_destroy_vm virt/kvm/kvm_main.c:1336 [inline] kvm_put_kvm+0xa6a/0x13f0 virt/kvm/kvm_main.c:1370 kvm_vm_release+0x46/0x50 virt/kvm/kvm_main.c:1393 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1581 [inline] free_pcp_prepare mm/page_alloc.c:1655 [inline] free_unref_page_prepare+0x81b/0x820 mm/page_alloc.c:3622 free_unref_page+0x93/0x530 mm/page_alloc.c:3720 free_the_page mm/page_alloc.c:863 [inline] __free_pages+0x67/0x100 mm/page_alloc.c:6021 free_pages+0x82/0x90 mm/page_alloc.c:6032 __stack_depot_save+0x45f/0x490 lib/stackdepot.c:506 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_set_track+0x60/0x70 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+0x12d/0x300 mm/slub.c:3737 kernfs_put+0x315/0x480 fs/kernfs/dir.c:568 sysfs_remove_group+0x238/0x250 fs/sysfs/group.c:319 netdev_queue_update_kobjects+0x3d6/0x470 net/core/net-sysfs.c:1725 remove_queue_kobjects net/core/net-sysfs.c:1824 [inline] netdev_unregister_kobject+0x106/0x260 net/core/net-sysfs.c:1977 unregister_netdevice_many+0x142c/0x1910 net/core/dev.c:11032 Memory state around the buggy address: ffff888120f97480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888120f97500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888120f97580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888120f97600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888120f97680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================