==================================================================
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 ffff888137557d50 by task syz.2.1989/6688

CPU: 1 PID: 6688 Comm: syz.2.1989 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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:1287
 __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:175
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:202
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:277
 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f23a16e3199
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:00007fff54f40b38 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f23a196cda0 RCX: 00007f23a16e3199
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f23a196cda0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007f23a196ccb0 R11: 0000000000000246 R12: 000000000008fc09
R13: 00007f23a196b18c R14: 000000000008fbd7 R15: 00007f23a196b180

Allocated by task 6689:
 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:1867 [inline]
 __sys_connect+0x3ce/0x450 net/socket.c:1884
 __do_sys_connect net/socket.c:1894 [inline]
 __se_sys_connect net/socket.c:1891 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:1891
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 6688:
 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:1287
 __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:175
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:202
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:277
 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:3521 [inline]
 addrconf_permanent_addr+0x302/0x940 net/ipv6/addrconf.c:3549
 addrconf_notify+0x752/0xea0 net/ipv6/addrconf.c:3617
 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:2052 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
 call_netdevice_notifiers net/core/dev.c:2078 [inline]
 __dev_notify_flags+0x2f4/0x5b0 net/core/dev.c:8583
 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8621
 do_setlink+0xb19/0x29a0 net/core/rtnetlink.c:2744
 __rtnl_newlink net/core/rtnetlink.c:3422 [inline]
 rtnl_newlink+0x13e6/0x1830 net/core/rtnetlink.c:3542
 rtnetlink_rcv_msg+0x9e9/0xca0 net/core/rtnetlink.c:5622
 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2508
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5640
 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:1919
 sock_sendmsg_nosec net/socket.c:652 [inline]
 __sock_sendmsg net/socket.c:664 [inline]
 __sys_sendto+0x467/0x620 net/socket.c:2007
 __do_sys_sendto net/socket.c:2019 [inline]
 __se_sys_sendto net/socket.c:2015 [inline]
 __x64_sys_sendto+0xe5/0x100 net/socket.c:2015
 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 ffff888137557c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 336 bytes inside of
 512-byte region [ffff888137557c00, ffff888137557e00)
The buggy address belongs to the page:
page:ffffea0004dd5500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x137554
head:ffffea0004dd5500 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100043080
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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 518, ts 36060023716, free_ts 29980342353
 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:1113
 inet6_addr_add+0x453/0x970 net/ipv6/addrconf.c:3023
 inet6_rtm_newaddr+0x6e1/0x9c0 net/ipv6/addrconf.c:4969
 rtnetlink_rcv_msg+0x9e9/0xca0 net/core/rtnetlink.c:5622
 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2508
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5640
 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:1919
 sock_sendmsg_nosec net/socket.c:652 [inline]
 __sock_sendmsg net/socket.c:664 [inline]
 __sys_sendto+0x467/0x620 net/socket.c:2007
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_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x129/0x9c0 mm/page_alloc.c:3443
 release_pages+0xe41/0xe90 mm/swap.c:1103
 __pagevec_release+0x71/0xe0 mm/swap.c:1123
 pagevec_release include/linux/pagevec.h:88 [inline]
 truncate_inode_pages_range+0x818/0x1650 mm/truncate.c:367
 truncate_inode_pages mm/truncate.c:473 [inline]
 truncate_inode_pages_final+0xc0/0xd0 mm/truncate.c:524
 f2fs_evict_inode+0x16d/0x14a0 fs/f2fs/inode.c:765
 evict+0x4a9/0x940 fs/inode.c:612
 dispose_list fs/inode.c:647 [inline]
 evict_inodes+0x620/0x6a0 fs/inode.c:701
 generic_shutdown_super+0x96/0x320 fs/super.c:454
 kill_block_super+0x7f/0xf0 fs/super.c:1480
 kill_f2fs_super+0x30a/0x3d0 fs/f2fs/super.c:4630
 deactivate_locked_super+0xa0/0x100 fs/super.c:335
 deactivate_super+0xaf/0xe0 fs/super.c:366
 cleanup_mnt+0x44f/0x500 fs/namespace.c:1123
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130

Memory state around the buggy address:
 ffff888137557c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888137557c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888137557d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888137557d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888137557e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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