================================================================== BUG: KASAN: use-after-free in rcu_segcblist_enqueue+0x9c/0xb0 kernel/rcu/rcu_segcblist.c:348 Write of size 8 at addr ffff88812f417190 by task udevd/101 CPU: 1 PID: 101 Comm: udevd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 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 dentry_free+0xbd/0x150 fs/dcache.c:-1 __dentry_kill+0x516/0x660 fs/dcache.c:600 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1 dput+0x47/0x90 fs/dcache.c:893 handle_mounts fs/namei.c:1514 [inline] step_into+0x8f8/0xce0 fs/namei.c:1814 walk_component+0x263/0x460 fs/namei.c:1990 lookup_last fs/namei.c:2439 [inline] path_lookupat+0x155/0x430 fs/namei.c:2463 filename_lookup+0x21e/0x550 fs/namei.c:2492 user_path_at_empty+0x46/0x1c0 fs/namei.c:2891 do_readlinkat+0xd9/0x490 fs/stat.c:442 __do_sys_readlink fs/stat.c:475 [inline] __se_sys_readlink fs/stat.c:472 [inline] __x64_sys_readlink+0x7f/0x90 fs/stat.c:472 x64_sys_call+0x93c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:90 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 RIP: 0033:0x7fca146bc3a7 Code: 00 00 90 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 00 31 c9 e8 8a 20 f9 ff 48 83 c4 18 c3 0f 1f 44 00 00 b8 59 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 21 ba 0d 00 f7 d8 64 89 02 48 RSP: 002b:00007ffc90649f98 EFLAGS: 00000202 ORIG_RAX: 0000000000000059 RAX: ffffffffffffffda RBX: 00007ffc9064a1a0 RCX: 00007fca146bc3a7 RDX: 0000000000000200 RSI: 00007ffc90649fa0 RDI: 00007ffc9064a1a0 RBP: 0000564fd2bcc2c0 R08: 0000000000000064 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffc90649fa0 R13: 0000564fcb08d100 R14: 0000564fd2e1fce0 R15: 00007ffc9064a7c0 Allocated by task 2054: 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:1923 [inline] __sys_connect+0x3cb/0x450 net/socket.c:1940 __do_sys_connect net/socket.c:1950 [inline] __se_sys_connect net/socket.c:1947 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:1947 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 1989: 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:1336 __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 ffff88812f417000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 400 bytes inside of 512-byte region [ffff88812f417000, ffff88812f417200) The buggy address belongs to the page: page:ffffea0004bd0500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12f414 head:ffffea0004bd0500 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 0000000b00000001 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 313, ts 26172820873, free_ts 0 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] __alloc_skb+0x210/0x730 net/core/skbuff.c:428 alloc_skb include/linux/skbuff.h:1183 [inline] nlmsg_new include/net/netlink.h:953 [inline] inet6_ifa_notify net/ipv6/addrconf.c:5543 [inline] __ipv6_ifa_notify+0x200/0xe70 net/ipv6/addrconf.c:6198 addrconf_ifdown+0xdb1/0x1910 net/ipv6/addrconf.c:3926 addrconf_notify+0x3bd/0xe00 net/ipv6/addrconf.c:-1 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:391 call_netdevice_notifiers_info net/core/dev.c:2070 [inline] call_netdevice_notifiers_extack net/core/dev.c:2082 [inline] call_netdevice_notifiers net/core/dev.c:2096 [inline] dev_close_many+0x325/0x4d0 net/core/dev.c:1671 unregister_netdevice_many+0x477/0x1a00 net/core/dev.c:11152 ip_tunnel_delete_nets+0x343/0x390 net/ipv4/ip_tunnel.c:1123 page_owner free stack trace missing Memory state around the buggy address: ffff88812f417080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88812f417100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88812f417180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88812f417200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88812f417280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc 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