================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline] BUG: KASAN: slab-use-after-free in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline] BUG: KASAN: slab-use-after-free in __refcount_add include/linux/refcount.h:193 [inline] BUG: KASAN: slab-use-after-free in __refcount_inc include/linux/refcount.h:250 [inline] BUG: KASAN: slab-use-after-free in refcount_inc include/linux/refcount.h:267 [inline] BUG: KASAN: slab-use-after-free in kref_get include/linux/kref.h:45 [inline] BUG: KASAN: slab-use-after-free in svc_get include/linux/sunrpc/svc.h:109 [inline] BUG: KASAN: slab-use-after-free in nfsd_shutdown_threads+0x8d/0x1a0 fs/nfsd/nfssvc.c:645 Write of size 4 at addr ffff88805d89e050 by task syz-executor/5770 CPU: 1 PID: 5770 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0xa8/0x210 mm/kasan/report.c:468 kasan_report+0x117/0x150 mm/kasan/report.c:581 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x241/0x290 mm/kasan/generic.c:187 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [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:109 [inline] nfsd_shutdown_threads+0x8d/0x1a0 fs/nfsd/nfssvc.c:645 nfsd_umount+0x42/0xc0 fs/nfsd/nfsctl.c:1464 deactivate_locked_super+0x97/0x100 fs/super.c:481 cleanup_mnt+0x3d7/0x460 fs/namespace.c:1259 task_work_run+0x1d4/0x260 kernel/task_work.c:245 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f2a2219f0d7 Code: a2 c7 05 1c 26 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:00007fff94f11668 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f2a2223330a RCX: 00007f2a2219f0d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff94f11720 RBP: 00007fff94f11720 R08: 00007fff94f12720 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff94f127b0 R13: 00007f2a2223330a R14: 000000000001b389 R15: 00007fff94f127f0 Allocated by task 6393: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:721 [inline] __svc_create+0x60/0xa20 net/sunrpc/svc.c:464 svc_create_pooled+0x66a/0x7e0 net/sunrpc/svc.c:556 nfsd_create_serv+0x29f/0x5c0 fs/nfsd/nfssvc.c:672 __write_ports_addfd fs/nfsd/nfsctl.c:712 [inline] __write_ports fs/nfsd/nfsctl.c:788 [inline] write_ports+0x698/0xfa0 fs/nfsd/nfsctl.c:844 nfsctl_transaction_write+0x10c/0x150 fs/nfsd/nfsctl.c:113 vfs_write+0x299/0x9a0 fs/read_write.c:582 ksys_write+0x151/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Freed by task 6393: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1811 [inline] slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837 slab_free mm/slub.c:3830 [inline] __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843 kref_put include/linux/kref.h:65 [inline] svc_put include/linux/sunrpc/svc.h:124 [inline] __write_ports_addfd fs/nfsd/nfsctl.c:724 [inline] __write_ports fs/nfsd/nfsctl.c:788 [inline] write_ports+0xb1a/0xfa0 fs/nfsd/nfsctl.c:844 nfsctl_transaction_write+0x10c/0x150 fs/nfsd/nfsctl.c:113 vfs_write+0x299/0x9a0 fs/read_write.c:582 ksys_write+0x151/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492 insert_work+0x3d/0x310 kernel/workqueue.c:1670 __queue_work+0xbfd/0xfd0 kernel/workqueue.c:1819 call_timer_fn+0x189/0x540 kernel/time/timer.c:1701 expire_timers kernel/time/timer.c:1747 [inline] __run_timers+0x59c/0x810 kernel/time/timer.c:2023 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036 handle_softirqs+0x27d/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 The buggy address belongs to the object at ffff88805d89e000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 80 bytes inside of freed 512-byte region [ffff88805d89e000, ffff88805d89e200) The buggy address belongs to the physical page: page:ffffea0001762700 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5d89c head:ffffea0001762700 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000840 ffff888017c41c80 ffffea0000b51e00 dead000000000002 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 59, tgid 59 (kworker/u4:4), ts 79661219943, free_ts 25858036257 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582 prep_new_page mm/page_alloc.c:1589 [inline] get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501 alloc_slab_page+0x5d/0x180 mm/slub.c:1881 allocate_slab mm/slub.c:2028 [inline] new_slab+0x87/0x2d0 mm/slub.c:2081 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253 __slab_alloc mm/slub.c:3339 [inline] __slab_alloc_node mm/slub.c:3392 [inline] slab_alloc_node mm/slub.c:3485 [inline] __kmem_cache_alloc_node+0x11f/0x250 mm/slub.c:3534 __do_kmalloc_node mm/slab_common.c:1006 [inline] __kmalloc+0xa7/0x240 mm/slab_common.c:1020 kmalloc include/linux/slab.h:604 [inline] kzalloc include/linux/slab.h:721 [inline] fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155 ip6_route_info_create+0x455/0x1260 net/ipv6/route.c:3805 ip6_route_add+0x28/0x160 net/ipv6/route.c:3901 addrconf_add_mroute net/ipv6/addrconf.c:2534 [inline] addrconf_add_dev+0x29c/0x3b0 net/ipv6/addrconf.c:2552 addrconf_dev_config net/ipv6/addrconf.c:3481 [inline] addrconf_init_auto_addrs+0x611/0xac0 net/ipv6/addrconf.c:3569 addrconf_notify+0xb62/0x1010 net/ipv6/addrconf.c:3742 notifier_call_chain+0x18f/0x380 kernel/notifier.c:93 netdev_state_change+0xe4/0x170 net/core/dev.c:1421 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1182 [inline] free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459 free_contig_range+0xa1/0x150 mm/page_alloc.c:6421 destroy_args+0x7d/0x840 mm/debug_vm_pgtable.c:1015 debug_vm_pgtable+0x411/0x440 mm/debug_vm_pgtable.c:1400 do_one_initcall+0x242/0x790 init/main.c:1249 do_initcall_level+0x13d/0x1f0 init/main.c:1311 do_initcalls+0x69/0xd0 init/main.c:1327 kernel_init_freeable+0x3d9/0x560 init/main.c:1564 kernel_init+0x1d/0x1c0 init/main.c:1454 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 Memory state around the buggy address: ffff88805d89df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88805d89df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88805d89e000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88805d89e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88805d89e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================