================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in atomic64_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:1515 [inline] BUG: KASAN: use-after-free in atomic_long_try_cmpxchg_acquire include/asm-generic/atomic-long.h:443 [inline] BUG: KASAN: use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:173 [inline] BUG: KASAN: use-after-free in mutex_lock+0x85/0xf0 kernel/locking/mutex.c:298 Write of size 8 at addr ffff88810d66f150 by task syz.4.727/2285 CPU: 0 PID: 2285 Comm: syz.4.727 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0x100/0x140 mm/kasan/report.c:452 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] atomic64_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:1515 [inline] atomic_long_try_cmpxchg_acquire include/asm-generic/atomic-long.h:443 [inline] __mutex_trylock_fast kernel/locking/mutex.c:173 [inline] mutex_lock+0x85/0xf0 kernel/locking/mutex.c:298 pppol2tp_release+0x178/0x2b0 net/l2tp/l2tp_ppp.c:442 __sock_release net/socket.c:597 [inline] sock_close+0xb8/0x200 net/socket.c:1286 __fput+0x2dc/0x730 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f1681c52e59 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:00007fff0f623068 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fff0f623150 RCX: 00007f1681c52e59 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 0000000000010bbc R08: 0000000000000001 R09: 0000000000000000 R10: 0000001b2d620000 R11: 0000000000000246 R12: 00007fff0f623190 R13: 00007f1681ecbfac R14: 0000000000010c50 R15: 00007f1681ecbfa0 Allocated by task 2286: 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:430 [inline] ____kasan_kmalloc mm/kasan/common.c:509 [inline] __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:518 kasan_kmalloc include/linux/kasan.h:254 [inline] __kmalloc+0x19f/0x330 mm/slub.c:4038 kmalloc include/linux/slab.h:560 [inline] kzalloc include/linux/slab.h:667 [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:1866 [inline] __sys_connect+0x3ce/0x450 net/socket.c:1883 __do_sys_connect net/socket.c:1893 [inline] __se_sys_connect net/socket.c:1890 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:1890 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Freed by task 2285: 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:362 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370 kasan_slab_free include/linux/kasan.h:220 [inline] slab_free_hook mm/slub.c:1600 [inline] slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626 slab_free mm/slub.c:3208 [inline] kfree+0xc0/0x270 mm/slub.c:4196 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline] l2tp_session_put+0xb2/0x1a0 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:597 [inline] sock_close+0xb8/0x200 net/socket.c:1286 __fput+0x2dc/0x730 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb 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 __call_rcu kernel/rcu/tree.c:2980 [inline] call_rcu+0x11a/0x1090 kernel/rcu/tree.c:3054 fib6_info_release include/net/ip6_fib.h:346 [inline] fixup_permanent_addr net/ipv6/addrconf.c:3515 [inline] addrconf_permanent_addr+0x302/0x940 net/ipv6/addrconf.c:3543 addrconf_notify+0x752/0xea0 net/ipv6/addrconf.c:3611 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410 call_netdevice_notifiers_info net/core/dev.c:2054 [inline] call_netdevice_notifiers_extack net/core/dev.c:2066 [inline] call_netdevice_notifiers net/core/dev.c:2080 [inline] __dev_notify_flags+0x2f4/0x5b0 net/core/dev.c:8585 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8623 do_setlink+0xb19/0x29a0 net/core/rtnetlink.c:2736 __rtnl_newlink net/core/rtnetlink.c:3414 [inline] rtnl_newlink+0x13e6/0x1830 net/core/rtnetlink.c:3534 rtnetlink_rcv_msg+0x9e9/0xca0 net/core/rtnetlink.c:5614 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2503 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5632 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x86c/0xa30 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x949/0xb70 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] __sys_sendto+0x467/0x620 net/socket.c:2006 __do_sys_sendto net/socket.c:2018 [inline] __se_sys_sendto net/socket.c:2014 [inline] __x64_sys_sendto+0xe5/0x100 net/socket.c:2014 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb The buggy address belongs to the object at ffff88810d66f000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 336 bytes inside of 512-byte region [ffff88810d66f000, ffff88810d66f200) The buggy address belongs to the page: page:ffffea0004359b00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10d66c head:ffffea0004359b00 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100043080 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 279, ts 20751211139, free_ts 20710013619 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x176/0x190 mm/page_alloc.c:2462 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1813 [inline] new_slab+0x84/0x3f0 mm/slub.c:1874 new_slab_objects mm/slub.c:2632 [inline] ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796 __slab_alloc+0x63/0xa0 mm/slub.c:2836 slab_alloc_node mm/slub.c:2918 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc_trace+0x1a8/0x2e0 mm/slub.c:2977 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:667 [inline] ipv6_add_addr+0x408/0xd90 net/ipv6/addrconf.c:1114 inet6_addr_add+0x453/0x970 net/ipv6/addrconf.c:3017 inet6_rtm_newaddr+0x6e1/0x9c0 net/ipv6/addrconf.c:4961 rtnetlink_rcv_msg+0x9e9/0xca0 net/core/rtnetlink.c:5614 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2503 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5632 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x86c/0xa30 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x949/0xb70 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] __sys_sendto+0x467/0x620 net/socket.c:2006 page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] __free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629 free_the_page mm/page_alloc.c:5445 [inline] __free_pages+0xd8/0x390 mm/page_alloc.c:5454 kfree+0x1e4/0x270 mm/slub.c:4193 kvfree+0x35/0x40 mm/util.c:647 btf_add_type kernel/bpf/btf.c:1421 [inline] btf_check_all_metas+0x42c/0x820 kernel/bpf/btf.c:3814 btf_parse_vmlinux+0x43e/0xab0 kernel/bpf/btf.c:4388 bpf_get_btf_vmlinux kernel/bpf/verifier.c:12570 [inline] bpf_check+0x5ed/0xdce0 kernel/bpf/verifier.c:12609 bpf_prog_load+0x1004/0x14e0 kernel/bpf/syscall.c:2234 __do_sys_bpf kernel/bpf/syscall.c:4435 [inline] __se_sys_bpf+0x49a/0x740 kernel/bpf/syscall.c:4391 __x64_sys_bpf+0x7b/0x90 kernel/bpf/syscall.c:4391 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Memory state around the buggy address: ffff88810d66f000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810d66f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88810d66f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88810d66f180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810d66f200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================