================================================================== 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 ffff888030696050 by task syz-executor/9806 CPU: 0 PID: 9806 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: 0033:0x7f7639f9f0d7 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:00007ffe7975e818 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f763a03330a RCX: 00007f7639f9f0d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe7975e8d0 RBP: 00007ffe7975e8d0 R08: 00007ffe7975f8d0 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe7975f960 R13: 00007f763a03330a R14: 000000000009e877 R15: 00007ffe7975f9a0 Allocated by task 13719: 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 13719: 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 __call_rcu_common kernel/rcu/tree.c:2721 [inline] call_rcu+0x153/0x900 kernel/rcu/tree.c:2837 in_dev_put include/linux/inetdevice.h:279 [inline] inet_rcu_free_ifa+0x77/0xc0 net/ipv4/devinet.c:228 rcu_do_batch kernel/rcu/tree.c:2194 [inline] rcu_core+0x9c1/0x17f0 kernel/rcu/tree.c:2467 handle_softirqs+0x27d/0x820 kernel/softirq.c:578 run_ksoftirqd+0xa8/0x100 kernel/softirq.c:950 smpboot_thread_fn+0x651/0x9f0 kernel/smpboot.c:164 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 The buggy address belongs to the object at ffff888030696000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 80 bytes inside of freed 512-byte region [ffff888030696000, ffff888030696200) The buggy address belongs to the physical page: page:ffffea0000c1a500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x30694 head:ffffea0000c1a500 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 dead000000000100 dead000000000122 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 4679, tgid 4679 (kworker/u4:10), ts 21823973992, free_ts 0 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 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:721 [inline] alloc_bprm+0x56/0x9a0 fs/exec.c:1538 kernel_execve+0x98/0x980 fs/exec.c:2023 call_usermodehelper_exec_async+0x20b/0x350 kernel/umh.c:110 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 page_owner free stack trace missing Memory state around the buggy address: ffff888030695f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888030695f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888030696000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888030696080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888030696100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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