================================================================== BUG: KASAN: slab-use-after-free in l2tp_tunnel_del_work+0xe5/0x330 net/l2tp/l2tp_core.c:1334 Read of size 8 at addr ffff8880683fa0b8 by task kworker/u8:5/170 CPU: 0 PID: 170 Comm: kworker/u8:5 Not tainted 6.10.0-rc4-syzkaller-00875-g568ebdaba637 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Workqueue: l2tp l2tp_tunnel_del_work Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 l2tp_tunnel_del_work+0xe5/0x330 net/l2tp/l2tp_core.c:1334 process_one_work kernel/workqueue.c:3231 [inline] process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312 worker_thread+0x86d/0xd70 kernel/workqueue.c:3393 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Allocated by task 5507: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:370 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slub.c:4122 [inline] __kmalloc_noprof+0x1f9/0x400 mm/slub.c:4135 kmalloc_noprof include/linux/slab.h:664 [inline] kzalloc_noprof include/linux/slab.h:778 [inline] l2tp_session_create+0x3b/0xc20 net/l2tp/l2tp_core.c:1675 pppol2tp_connect+0xca3/0x17a0 net/l2tp/l2tp_ppp.c:782 __sys_connect_file net/socket.c:2049 [inline] __sys_connect+0x2df/0x310 net/socket.c:2066 __do_sys_connect net/socket.c:2076 [inline] __se_sys_connect net/socket.c:2073 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2073 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 24: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579 poison_slab_object+0xe0/0x150 mm/kasan/common.c:240 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256 kasan_slab_free include/linux/kasan.h:184 [inline] slab_free_hook mm/slub.c:2196 [inline] slab_free mm/slub.c:4437 [inline] kfree+0x149/0x360 mm/slub.c:4558 __sk_destruct+0x58/0x5f0 net/core/sock.c:2191 rcu_do_batch kernel/rcu/tree.c:2535 [inline] rcu_core+0xafd/0x1830 kernel/rcu/tree.c:2809 handle_softirqs+0x2c4/0x970 kernel/softirq.c:554 run_ksoftirqd+0xca/0x130 kernel/softirq.c:928 smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Last potentially related work creation: kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47 __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541 __call_rcu_common kernel/rcu/tree.c:3072 [inline] call_rcu+0x167/0xa70 kernel/rcu/tree.c:3176 pppol2tp_release+0x24b/0x350 net/l2tp/l2tp_ppp.c:457 __sock_release net/socket.c:659 [inline] sock_close+0xbc/0x240 net/socket.c:1421 __fput+0x406/0x8b0 fs/file_table.c:422 task_work_run+0x24f/0x310 kernel/task_work.c:180 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff8880683fa000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 184 bytes inside of freed 1024-byte region [ffff8880683fa000, ffff8880683fa400) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x683f8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffefff(slab) raw: 00fff00000000040 ffff888015041dc0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000 head: 00fff00000000040 ffff888015041dc0 0000000000000000 dead000000000001 head: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000 head: 00fff00000000003 ffffea0001a0fe01 ffffffffffffffff 0000000000000000 head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5100, tgid 5100 (syz-executor), ts 63849897657, free_ts 16360508115 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1468 prep_new_page mm/page_alloc.c:1476 [inline] get_page_from_freelist+0x2e43/0x2f00 mm/page_alloc.c:3420 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4678 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline] alloc_pages_node_noprof include/linux/gfp.h:296 [inline] alloc_slab_page+0x5f/0x120 mm/slub.c:2265 allocate_slab+0x5a/0x2f0 mm/slub.c:2428 new_slab mm/slub.c:2481 [inline] ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3667 __slab_alloc+0x58/0xa0 mm/slub.c:3757 __slab_alloc_node mm/slub.c:3810 [inline] slab_alloc_node mm/slub.c:3989 [inline] __do_kmalloc_node mm/slub.c:4121 [inline] __kmalloc_node_noprof+0x286/0x440 mm/slub.c:4129 kmalloc_node_noprof include/linux/slab.h:681 [inline] qdisc_alloc+0x97/0xa80 net/sched/sch_generic.c:946 qdisc_create_dflt+0x62/0x4b0 net/sched/sch_generic.c:1008 attach_one_default_qdisc net/sched/sch_generic.c:1174 [inline] netdev_for_each_tx_queue include/linux/netdevice.h:2504 [inline] attach_default_qdiscs net/sched/sch_generic.c:1192 [inline] dev_activate+0x3c0/0x1240 net/sched/sch_generic.c:1251 __dev_open+0x352/0x450 net/core/dev.c:1481 __dev_change_flags+0x1e2/0x6f0 net/core/dev.c:8781 dev_change_flags+0x8b/0x1a0 net/core/dev.c:8853 do_setlink+0xccd/0x41f0 net/core/rtnetlink.c:2900 __rtnl_newlink net/core/rtnetlink.c:3696 [inline] rtnl_newlink+0x180d/0x20a0 net/core/rtnetlink.c:3743 page last free pid 1 tgid 1 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1088 [inline] free_unref_page+0xd22/0xea0 mm/page_alloc.c:2583 free_contig_range+0x9e/0x160 mm/page_alloc.c:6637 destroy_args+0x8a/0x890 mm/debug_vm_pgtable.c:1017 debug_vm_pgtable+0x4be/0x550 mm/debug_vm_pgtable.c:1397 do_one_initcall+0x248/0x880 init/main.c:1267 do_initcall_level+0x157/0x210 init/main.c:1329 do_initcalls+0x3f/0x80 init/main.c:1345 kernel_init_freeable+0x435/0x5d0 init/main.c:1578 kernel_init+0x1d/0x2b0 init/main.c:1467 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Memory state around the buggy address: ffff8880683f9f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880683fa000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880683fa080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880683fa100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880683fa180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================