================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline] BUG: KASAN: use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1779 [inline] BUG: KASAN: use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:176 [inline] BUG: KASAN: use-after-free in mutex_lock+0x86/0x1b0 kernel/locking/mutex.c:295 Write of size 8 at addr ffff88810dc9bd50 by task syz.0.1196/4752 CPU: 0 PID: 4752 Comm: syz.0.1196 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 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 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:102 [inline] atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1779 [inline] __mutex_trylock_fast kernel/locking/mutex.c:176 [inline] mutex_lock+0x86/0x1b0 kernel/locking/mutex.c:295 pppol2tp_release+0x194/0x2d0 net/l2tp/l2tp_ppp.c:441 __sock_release net/socket.c:652 [inline] sock_close+0xf1/0x290 net/socket.c:1389 __fput+0x1fc/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+0xa35/0x2660 kernel/exit.c:886 do_group_exit+0x225/0x2e0 kernel/exit.c:1029 get_signal+0x13b5/0x1520 kernel/signal.c:2891 arch_do_signal_or_restart+0xd1/0x1140 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fe9a019ce59 Code: Unable to access opcode bytes at 0x7fe9a019ce2f. RSP: 002b:00007fe9a11270e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007fe9a0415fa8 RCX: 00007fe9a019ce59 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fe9a0415fa8 RBP: 00007fe9a0415fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe9a0416038 R14: 00007ffc80c1e1d0 R15: 00007ffc80c1e2b8 Allocated by task 4752: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_alloc_info+0x25/0x30 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+0xb1/0x1e0 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:1609 pppol2tp_connect+0xbef/0x1620 net/l2tp/l2tp_ppp.c:771 __sys_connect_file net/socket.c:2000 [inline] __sys_connect+0x3da/0x460 net/socket.c:2017 __do_sys_connect net/socket.c:2027 [inline] __se_sys_connect net/socket.c:2024 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2024 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 4752: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x31/0x50 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+0x3f0/0x4e0 net/l2tp/l2tp_core.c:1582 pppol2tp_release+0x185/0x2d0 net/l2tp/l2tp_ppp.c:438 __sock_release net/socket.c:652 [inline] sock_close+0xf1/0x290 net/socket.c:1389 __fput+0x1fc/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+0xa35/0x2660 kernel/exit.c:886 do_group_exit+0x225/0x2e0 kernel/exit.c:1029 get_signal+0x13b5/0x1520 kernel/signal.c:2891 arch_do_signal_or_restart+0xd1/0x1140 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 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 kvfree_call_rcu+0x8b/0x7c0 kernel/rcu/tree.c:3445 drop_sysctl_table+0x2f5/0x430 fs/proc/proc_sysctl.c:1731 drop_sysctl_table+0x2e4/0x430 fs/proc/proc_sysctl.c:1734 unregister_sysctl_table+0x75/0x120 fs/proc/proc_sysctl.c:1769 unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:175 __devinet_sysctl_unregister net/ipv4/devinet.c:2635 [inline] devinet_sysctl_unregister net/ipv4/devinet.c:2663 [inline] inetdev_destroy net/ipv4/devinet.c:329 [inline] inetdev_event+0x80b/0x10e0 net/ipv4/devinet.c:1615 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xa1/0x110 kernel/notifier.c:455 call_netdevice_notifiers_info net/core/dev.c:2022 [inline] call_netdevice_notifiers_extack net/core/dev.c:2060 [inline] call_netdevice_notifiers net/core/dev.c:2074 [inline] unregister_netdevice_many+0x102c/0x18e0 net/core/dev.c:11005 default_device_exit_batch+0x9dc/0xa70 net/core/dev.c:11518 ops_exit_list net/core/net_namespace.c:177 [inline] cleanup_net+0x635/0xb10 net/core/net_namespace.c:604 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302 worker_thread+0xa29/0x11e0 kernel/workqueue.c:2449 kthread+0x281/0x320 kernel/kthread.c:386 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 The buggy address belongs to the object at ffff88810dc9bc00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 336 bytes inside of 512-byte region [ffff88810dc9bc00, ffff88810dc9be00) The buggy address belongs to the physical page: page:ffffea0004372600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10dc98 head:ffffea0004372600 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 ffffea0004c3fc00 dead000000000002 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 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 2266528108, free_ts 0 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672 prep_new_page+0x1c/0x110 mm/page_alloc.c:2679 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4585 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5929 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1 allocate_slab mm/slub.c:1967 [inline] new_slab+0x98/0x3d0 mm/slub.c:2020 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3177 __slab_alloc+0x5e/0xa0 mm/slub.c:3263 slab_alloc_node mm/slub.c:3348 [inline] __kmem_cache_alloc_node+0x203/0x2c0 mm/slub.c:3423 kmalloc_trace+0x29/0xb0 mm/slab_common.c:1028 kmalloc include/linux/slab.h:563 [inline] usb_cache_string+0x66/0x130 drivers/usb/core/message.c:1085 usb_enumerate_device drivers/usb/core/hub.c:2527 [inline] usb_new_device+0x2fa/0x1550 drivers/usb/core/hub.c:2654 register_root_hub+0x26c/0x490 drivers/usb/core/hcd.c:1021 usb_add_hcd+0xaad/0xea0 drivers/usb/core/hcd.c:3001 dummy_hcd_probe+0x14a/0x290 drivers/usb/gadget/udc/dummy_hcd.c:2705 platform_probe+0x16d/0x1f0 drivers/base/platform.c:1400 page_owner free stack trace missing Memory state around the buggy address: ffff88810dc9bc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810dc9bc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88810dc9bd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88810dc9bd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810dc9be00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================