================================================================== 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 ffff88812158a150 by task syz.6.479/2493 CPU: 0 PID: 2493 Comm: syz.6.479 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 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+0x178/0x2b0 net/l2tp/l2tp_ppp.c:441 __sock_release net/socket.c:652 [inline] sock_close+0xc9/0x220 net/socket.c:1389 __fput+0x1fd/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+0xaf2/0x2850 kernel/exit.c:887 __do_sys_exit kernel/exit.c:996 [inline] __se_sys_exit kernel/exit.c:994 [inline] __x64_sys_exit+0x40/0x40 kernel/exit.c:994 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61 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 RIP: 0033:0x7f359279e0d9 Code: Unable to access opcode bytes at 0x7f359279e0af. RSP: 002b:00007f35935c2ef8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f359279e0d9 RDX: 00007f35935c39c8 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f3592835024 R08: 0000000000000000 R09: 0000000000000058 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3592a26038 R14: 00007f3592a25fa0 R15: 00007fffb3b24b68 Allocated by task 2484: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_alloc_info+0x1f/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+0xb4/0x1e0 mm/slab_common.c:951 kmalloc include/linux/slab.h:568 [inline] kzalloc include/linux/slab.h:699 [inline] l2tp_session_create+0x38/0xbd0 net/l2tp/l2tp_core.c:1609 pppol2tp_connect+0xbf5/0x1640 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 2493: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x2b/0x40 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+0x3df/0x4d0 net/l2tp/l2tp_core.c:1582 pppol2tp_release+0x169/0x2b0 net/l2tp/l2tp_ppp.c:438 __sock_release net/socket.c:652 [inline] sock_close+0xc9/0x220 net/socket.c:1389 __fput+0x1fd/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+0xaf2/0x2850 kernel/exit.c:887 __do_sys_exit kernel/exit.c:996 [inline] __se_sys_exit kernel/exit.c:994 [inline] __cfi___ia32_sys_exit+0x0/0x10 kernel/exit.c:994 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61 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 The buggy address belongs to the object at ffff88812158a000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 336 bytes inside of 512-byte region [ffff88812158a000, ffff88812158a200) The buggy address belongs to the physical page: page:ffffea0004856200 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88812158a400 pfn:0x121588 head:ffffea0004856200 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 ffffea0004370a08 ffffea0004380608 ffff888100042f00 raw: ffff88812158a400 0000000000100005 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 1948, tgid 1948 (syz-executor), ts 125399885434, free_ts 123842214906 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+0x2ca9/0x2d20 mm/page_alloc.c:4586 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1 allocate_slab mm/slub.c:1967 [inline] new_slab+0x98/0x3e0 mm/slub.c:2020 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177 __slab_alloc+0x5e/0xa0 mm/slub.c:3263 slab_alloc_node mm/slub.c:3348 [inline] __kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423 __do_kmalloc_node mm/slab_common.c:937 [inline] __kmalloc_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958 kmalloc_reserve net/core/skbuff.c:449 [inline] __alloc_skb+0x226/0x4a0 net/core/skbuff.c:518 alloc_skb include/linux/skbuff.h:1322 [inline] nlmsg_new include/net/netlink.h:987 [inline] netlink_ack+0x373/0x1160 net/netlink/af_netlink.c:2458 netlink_rcv_skb+0x27e/0x450 net/netlink/af_netlink.c:2527 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6171 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x8c1/0xa60 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x8b9/0xbd0 net/netlink/af_netlink.c:1873 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1580 [inline] free_pcp_prepare mm/page_alloc.c:1654 [inline] free_unref_page_prepare+0x80c/0x820 mm/page_alloc.c:3621 free_unref_page+0x93/0x530 mm/page_alloc.c:3719 free_the_page mm/page_alloc.c:863 [inline] free_compound_page+0x99/0xd0 mm/page_alloc.c:886 destroy_large_folio+0x68/0xa0 mm/page_alloc.c:923 __folio_put_large mm/swap.c:113 [inline] __folio_put+0xd1/0xe0 mm/swap.c:121 folio_put include/linux/mm.h:1442 [inline] put_page include/linux/mm.h:1494 [inline] page_to_skb+0x4e1/0xb50 drivers/net/virtio_net.c:565 receive_mergeable drivers/net/virtio_net.c:1158 [inline] receive_buf+0x469/0x4890 drivers/net/virtio_net.c:1297 virtnet_receive drivers/net/virtio_net.c:1592 [inline] virtnet_poll+0x5c9/0x1150 drivers/net/virtio_net.c:1710 __napi_poll+0xcd/0x5d0 net/core/dev.c:6644 napi_poll net/core/dev.c:6711 [inline] net_rx_action+0x4a3/0xa90 net/core/dev.c:6825 handle_softirqs+0x1d7/0x600 kernel/softirq.c:642 __do_softirq kernel/softirq.c:680 [inline] invoke_softirq kernel/softirq.c:497 [inline] __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:729 irq_exit_rcu+0x9/0x10 kernel/softirq.c:741 common_interrupt+0xbe/0xe0 arch/x86/kernel/irq.c:242 asm_common_interrupt+0x27/0x40 arch/x86/include/asm/idtentry.h:682 Memory state around the buggy address: ffff88812158a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88812158a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88812158a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88812158a180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88812158a200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================