================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1667 [inline] BUG: KASAN: use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:169 [inline] BUG: KASAN: use-after-free in mutex_lock+0x8e/0x1c0 kernel/locking/mutex.c:288 Write of size 8 at addr ffff888128279150 by task syz.1.457/1995 CPU: 1 PID: 1995 Comm: syz.1.457 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 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 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1667 [inline] __mutex_trylock_fast kernel/locking/mutex.c:169 [inline] mutex_lock+0x8e/0x1c0 kernel/locking/mutex.c:288 pppol2tp_release+0x178/0x2b0 net/l2tp/l2tp_ppp.c:442 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x200 net/socket.c:1335 __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 RIP: 0033:0x7f9a3ecd2e59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe14433988 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007ffe14433a70 RCX: 00007f9a3ecd2e59 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 0000000000017ae9 R08: 0000000000000001 R09: 0000000000000000 R10: 0000001b2d920000 R11: 0000000000000246 R12: 00007ffe14433ab0 R13: 00007f9a3ef4bfac R14: 0000000000017b1d R15: 00007f9a3ef4bfa0 Allocated by task 1996: 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:1922 [inline] __sys_connect+0x3cb/0x450 net/socket.c:1939 __do_sys_connect net/socket.c:1949 [inline] __se_sys_connect net/socket.c:1946 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:1946 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 1995: 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 pppol2tp_release+0x169/0x2b0 net/l2tp/l2tp_ppp.c:439 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x200 net/socket.c:1335 __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 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 kvfree_call_rcu+0xb6/0x860 kernel/rcu/tree.c:3648 drop_sysctl_table+0x2f5/0x430 fs/proc/proc_sysctl.c:1687 drop_sysctl_table+0x2e4/0x430 fs/proc/proc_sysctl.c:1690 unregister_sysctl_table+0x7a/0x120 fs/proc/proc_sysctl.c:1725 unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:175 __devinet_sysctl_unregister net/ipv4/devinet.c:2627 [inline] devinet_sysctl_unregister net/ipv4/devinet.c:2655 [inline] inetdev_destroy net/ipv4/devinet.c:327 [inline] inetdev_event+0x788/0x1060 net/ipv4/devinet.c:1612 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] unregister_netdevice_many+0x103d/0x1a00 net/core/dev.c:11176 default_device_exit_batch+0x35e/0x3c0 net/core/dev.c:11709 ops_exit_list net/core/net_namespace.c:177 [inline] cleanup_net+0x605/0xae0 net/core/net_namespace.c:599 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 The buggy address belongs to the object at ffff888128279000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 336 bytes inside of 512-byte region [ffff888128279000, ffff888128279200) The buggy address belongs to the page: page:ffffea0004a09e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88812827bc00 pfn:0x128278 head:ffffea0004a09e00 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042f00 raw: ffff88812827bc00 000000008010000f 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 288, ts 22482072555, 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+0x16a/0x2c0 mm/slub.c:4432 kmalloc include/linux/slab.h:624 [inline] kzalloc include/linux/slab.h:750 [inline] new_dir fs/proc/proc_sysctl.c:961 [inline] get_subdir fs/proc/proc_sysctl.c:1006 [inline] __register_sysctl_table+0xa35/0x1240 fs/proc/proc_sysctl.c:1355 register_net_sysctl+0x21d/0x230 net/sysctl_net.c:169 neigh_sysctl_register+0x9a9/0xa90 net/core/neighbour.c:3718 devinet_sysctl_register+0xaf/0x1e0 net/ipv4/devinet.c:2641 inetdev_init+0x2b2/0x500 net/ipv4/devinet.c:284 inetdev_event+0x1f4/0x1060 net/ipv4/devinet.c:1544 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+0x119/0x190 net/core/dev.c:2096 page_owner free stack trace missing Memory state around the buggy address: ffff888128279000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888128279080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888128279100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888128279180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888128279200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================