================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline] BUG: KASAN: use-after-free in test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline] BUG: KASAN: use-after-free in l2tp_session_delete+0x27/0x520 net/l2tp/l2tp_core.c:1561 Write of size 8 at addr ffff88812b5eac08 by task kworker/u4:5/14017 CPU: 1 PID: 14017 Comm: kworker/u4:5 Tainted: G W 6.1.128-syzkaller-00040-g6b227a1f7460 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: l2tp l2tp_tunnel_del_work Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0x158/0x4e0 mm/kasan/report.c:427 kasan_report+0x13c/0x170 mm/kasan/report.c:531 kasan_check_range+0x294/0x2a0 mm/kasan/generic.c:189 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37 instrument_atomic_read_write include/linux/instrumented.h:102 [inline] test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline] l2tp_session_delete+0x27/0x520 net/l2tp/l2tp_core.c:1561 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1216 [inline] l2tp_tunnel_del_work+0x1f8/0x400 net/l2tp/l2tp_core.c:1256 process_one_work+0x73d/0xcb0 kernel/workqueue.c:2299 worker_thread+0xa60/0x1260 kernel/workqueue.c:2446 kthread+0x26d/0x300 kernel/kthread.c:386 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Allocated by task 15364: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:379 [inline] __kasan_kmalloc+0x9c/0xb0 mm/kasan/common.c:388 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+0x38/0xbe0 net/l2tp/l2tp_core.c:1597 pppol2tp_connect+0xc5d/0x1690 net/l2tp/l2tp_ppp.c:781 __sys_connect_file net/socket.c:2001 [inline] __sys_connect+0x2c9/0x300 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+0x14e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Freed by task 15347: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516 ____kasan_slab_free+0x131/0x180 mm/kasan/common.c:241 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:249 kasan_slab_free include/linux/kasan.h:178 [inline] slab_free_hook mm/slub.c:1745 [inline] slab_free_freelist_hook mm/slub.c:1771 [inline] slab_free mm/slub.c:3686 [inline] __kmem_cache_free+0x21d/0x410 mm/slub.c:3702 kfree+0x7a/0xf0 mm/slab_common.c:990 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline] l2tp_session_dec_refcount+0xa9/0x1b0 net/l2tp/l2tp_core.c:205 pppol2tp_session_destruct+0xaf/0xf0 net/l2tp/l2tp_ppp.c:418 __sk_destruct+0x56/0x5c0 net/core/sock.c:2148 sk_destruct net/core/sock.c:2193 [inline] __sk_free+0x36c/0x470 net/core/sock.c:2204 sk_free+0x51/0x80 net/core/sock.c:2215 sock_put include/net/sock.h:2049 [inline] pppol2tp_put_sk+0x77/0xb0 net/l2tp/l2tp_ppp.c:401 rcu_do_batch+0x552/0xbe0 kernel/rcu/tree.c:2297 rcu_core+0x502/0xf40 kernel/rcu/tree.c:2557 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574 handle_softirqs+0x1db/0x650 kernel/softirq.c:624 __do_softirq kernel/softirq.c:662 [inline] invoke_softirq kernel/softirq.c:479 [inline] __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:711 irq_exit_rcu+0x9/0x10 kernel/softirq.c:723 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:691 Last potentially related work creation: kasan_save_stack+0x3b/0x60 mm/kasan/common.c:45 __kasan_record_aux_stack+0xb4/0xc0 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+0xdc/0x10f0 kernel/rcu/tree.c:2926 pppol2tp_release+0x20f/0x2d0 net/l2tp/l2tp_ppp.c:457 __sock_release net/socket.c:652 [inline] sock_close+0xdf/0x270 net/socket.c:1390 __fput+0x1e5/0x870 fs/file_table.c:320 ____fput+0x15/0x20 fs/file_table.c:348 task_work_run+0x24d/0x2e0 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0x94/0xa0 kernel/entry/common.c:177 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x26/0x130 kernel/entry/common.c:303 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 The buggy address belongs to the object at ffff88812b5eac00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 8 bytes inside of 512-byte region [ffff88812b5eac00, ffff88812b5eae00) The buggy address belongs to the physical page: page:ffffea0004ad7a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12b5e8 head:ffffea0004ad7a00 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 dead000000000100 dead000000000122 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 11096, tgid 11095 (syz.5.3502), ts 532244646698, free_ts 523471490583 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x213/0x220 mm/page_alloc.c:2637 prep_new_page+0x1b/0x110 mm/page_alloc.c:2644 get_page_from_freelist+0x3a98/0x3b10 mm/page_alloc.c:4539 __alloc_pages+0x234/0x610 mm/page_alloc.c:5837 alloc_slab_page+0x6c/0xf0 allocate_slab mm/slub.c:1962 [inline] new_slab+0x90/0x3e0 mm/slub.c:2015 ___slab_alloc+0x6f9/0xb80 mm/slub.c:3203 __slab_alloc+0x5d/0xa0 mm/slub.c:3302 slab_alloc_node mm/slub.c:3387 [inline] __kmem_cache_alloc_node+0x207/0x2a0 mm/slub.c:3462 __do_kmalloc_node mm/slab_common.c:937 [inline] __kmalloc_node_track_caller+0xa2/0x1e0 mm/slab_common.c:958 kmalloc_reserve net/core/skbuff.c:446 [inline] __alloc_skb+0x125/0x2d0 net/core/skbuff.c:515 alloc_skb include/linux/skbuff.h:1290 [inline] alloc_skb_with_frags+0xa6/0x680 net/core/skbuff.c:6162 sock_alloc_send_pskb+0x915/0xa50 net/core/sock.c:2756 unix_dgram_sendmsg+0x5b1/0x2050 net/unix/af_unix.c:1920 sock_sendmsg_nosec net/socket.c:716 [inline] __sock_sendmsg net/socket.c:728 [inline] ____sys_sendmsg+0x5d3/0x9a0 net/socket.c:2509 ___sys_sendmsg net/socket.c:2563 [inline] __sys_sendmmsg+0x3b9/0x6f0 net/socket.c:2649 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1545 [inline] free_pcp_prepare mm/page_alloc.c:1619 [inline] free_unref_page_prepare+0x9f1/0xa00 mm/page_alloc.c:3581 free_unref_page+0xb2/0x5c0 mm/page_alloc.c:3677 free_the_page mm/page_alloc.c:830 [inline] __free_pages+0x61/0xf0 mm/page_alloc.c:5926 __free_slab+0xce/0x1a0 mm/slub.c:2039 free_slab mm/slub.c:2054 [inline] discard_slab+0x29/0x40 mm/slub.c:2060 __slab_free+0x205/0x280 mm/slub.c:3599 do_slab_free mm/slub.c:3640 [inline] ___cache_free+0xc6/0xd0 mm/slub.c:3696 qlink_free mm/kasan/quarantine.c:168 [inline] qlist_free_all+0xc5/0x140 mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x15a/0x180 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0x24/0x80 mm/kasan/common.c:310 kasan_slab_alloc include/linux/kasan.h:202 [inline] slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:768 slab_alloc_node mm/slub.c:3421 [inline] __kmem_cache_alloc_node+0x193/0x2a0 mm/slub.c:3462 __do_kmalloc_node mm/slab_common.c:937 [inline] __kmalloc+0xa3/0x1e0 mm/slab_common.c:951 kmalloc_array include/linux/slab.h:615 [inline] kcalloc include/linux/slab.h:646 [inline] iter_file_splice_write+0x278/0xf90 fs/splice.c:624 do_splice_from fs/splice.c:763 [inline] direct_splice_actor+0xff/0x130 fs/splice.c:930 splice_direct_to_actor+0x4b4/0xbb0 fs/splice.c:885 Memory state around the buggy address: ffff88812b5eab00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88812b5eab80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88812b5eac00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88812b5eac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88812b5ead00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================