================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline] BUG: KASAN: use-after-free in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline] BUG: KASAN: use-after-free in __refcount_add include/linux/refcount.h:193 [inline] BUG: KASAN: use-after-free in __refcount_inc include/linux/refcount.h:250 [inline] BUG: KASAN: use-after-free in refcount_inc include/linux/refcount.h:267 [inline] BUG: KASAN: use-after-free in kref_get include/linux/kref.h:45 [inline] BUG: KASAN: use-after-free in svc_get include/linux/sunrpc/svc.h:108 [inline] BUG: KASAN: use-after-free in nfsd_shutdown_threads+0x89/0x1a0 fs/nfsd/nfssvc.c:640 Write of size 4 at addr ffff8880775cfc50 by task syz-executor/4284 CPU: 0 PID: 4284 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0xa8/0x210 mm/kasan/report.c:420 kasan_report+0x10b/0x140 mm/kasan/report.c:524 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x235/0x290 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:102 [inline] atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline] __refcount_add include/linux/refcount.h:193 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] svc_get include/linux/sunrpc/svc.h:108 [inline] nfsd_shutdown_threads+0x89/0x1a0 fs/nfsd/nfssvc.c:640 nfsd_umount+0x3e/0xc0 fs/nfsd/nfsctl.c:1409 deactivate_locked_super+0x93/0xf0 fs/super.c:332 cleanup_mnt+0x471/0x4f0 fs/namespace.c:1191 task_work_run+0x1d0/0x260 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213 __syscall_exit_to_user_mode_work kernel/entry/common.c:295 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:306 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fe1fff9f3d7 Code: a2 c7 05 1c 63 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007ffc1f605ad8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007fe200034d23 RCX: 00007fe1fff9f3d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc1f605b90 RBP: 00007ffc1f605b90 R08: 00007ffc1f606b90 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc1f606c20 R13: 00007fe200034d23 R14: 0000000000019602 R15: 00007ffc1f606c60 Allocated by task 4855: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] __svc_create+0x60/0x9d0 net/sunrpc/svc.c:491 svc_create_pooled+0x71f/0x8c0 net/sunrpc/svc.c:579 nfsd_create_serv+0x2f9/0x700 fs/nfsd/nfssvc.c:667 __write_ports_addfd fs/nfsd/nfsctl.c:716 [inline] __write_ports fs/nfsd/nfsctl.c:791 [inline] write_ports+0x526/0xb80 fs/nfsd/nfsctl.c:847 nfsctl_transaction_write+0x105/0x150 fs/nfsd/nfsctl.c:114 vfs_write+0x2dc/0x9a0 fs/read_write.c:582 ksys_write+0x14d/0x260 fs/read_write.c:637 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 4855: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xb6/0x200 mm/slub.c:3700 kref_put include/linux/kref.h:65 [inline] svc_put include/linux/sunrpc/svc.h:123 [inline] __write_ports_addfd fs/nfsd/nfsctl.c:728 [inline] __write_ports fs/nfsd/nfsctl.c:791 [inline] write_ports+0x9ac/0xb80 fs/nfsd/nfsctl.c:847 nfsctl_transaction_write+0x105/0x150 fs/nfsd/nfsctl.c:114 vfs_write+0x2dc/0x9a0 fs/read_write.c:582 ksys_write+0x14d/0x260 fs/read_write.c:637 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 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486 call_rcu+0x14f/0x950 kernel/rcu/tree.c:2849 fib6_info_release include/net/ip6_fib.h:342 [inline] ip6_route_info_create+0x9e4/0x1220 net/ipv6/route.c:3882 ip6_route_add+0x24/0x130 net/ipv6/route.c:3896 addrconf_prefix_route+0x249/0x320 net/ipv6/addrconf.c:2450 inet6_addr_add+0x502/0x9c0 net/ipv6/addrconf.c:3031 inet6_rtm_newaddr+0x6c9/0x8f0 net/ipv6/addrconf.c:4988 rtnetlink_rcv_msg+0x863/0xfb0 net/core/rtnetlink.c:6166 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] __sys_sendto+0x497/0x650 net/socket.c:2153 __do_sys_sendto net/socket.c:2165 [inline] __se_sys_sendto net/socket.c:2161 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:2161 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 ffff8880775cfc00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 80 bytes inside of 512-byte region [ffff8880775cfc00, ffff8880775cfe00) The buggy address belongs to the physical page: page:ffffea0001dd7300 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x775cc head:ffffea0001dd7300 order:2 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888017441c80 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4313, tgid 4313 (kworker/1:4), ts 68798593765, free_ts 63358984313 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560 prep_new_page mm/page_alloc.c:2567 [inline] get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658 alloc_slab_page+0x5d/0x180 mm/slub.c:1799 allocate_slab mm/slub.c:1944 [inline] new_slab+0x87/0x2d0 mm/slub.c:1997 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3154 __slab_alloc mm/slub.c:3240 [inline] slab_alloc_node mm/slub.c:3325 [inline] __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] mca_alloc net/ipv6/mcast.c:887 [inline] __ipv6_dev_mc_inc+0x47b/0xb20 net/ipv6/mcast.c:942 addrconf_join_solict net/ipv6/addrconf.c:2205 [inline] addrconf_dad_begin net/ipv6/addrconf.c:4054 [inline] addrconf_dad_work+0x3b8/0x1500 net/ipv6/addrconf.c:4179 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1487 [inline] free_pcp_prepare mm/page_alloc.c:1537 [inline] free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509 qlink_free mm/kasan/quarantine.c:168 [inline] qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737 slab_alloc_node mm/slub.c:3359 [inline] __kmem_cache_alloc_node+0x19d/0x270 mm/slub.c:3398 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] kset_create lib/kobject.c:950 [inline] kset_create_and_add+0x56/0x160 lib/kobject.c:993 register_queue_kobjects net/core/net-sysfs.c:1764 [inline] netdev_register_kobject+0x1ae/0x320 net/core/net-sysfs.c:2017 register_netdevice+0x133a/0x1b80 net/core/dev.c:10243 wg_newlink+0x455/0x720 drivers/net/wireguard/device.c:371 rtnl_newlink_create net/core/rtnetlink.c:3436 [inline] __rtnl_newlink net/core/rtnetlink.c:3656 [inline] rtnl_newlink+0x14b3/0x1f90 net/core/rtnetlink.c:3669 rtnetlink_rcv_msg+0x863/0xfb0 net/core/rtnetlink.c:6166 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344 Memory state around the buggy address: ffff8880775cfb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880775cfb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880775cfc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880775cfc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880775cfd00: fb 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