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BUG: KASAN: use-after-free in nfsd_nrthreads+0xf8/0xfc fs/nfsd/nfssvc.c:282
Read of size 4 at addr ffff0000f58f3054 by task syz.4.1965/10872

CPU: 0 PID: 10872 Comm: syz.4.1965 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load4_noabort+0x2c/0x38 mm/kasan/report_generic.c:350
 nfsd_nrthreads+0xf8/0xfc fs/nfsd/nfssvc.c:282
 write_threads+0x1c0/0x310 fs/nfsd/nfsctl.c:428
 nfsctl_transaction_write+0x114/0x164 fs/nfsd/nfsctl.c:114
 vfs_write+0x2a8/0x7c8 fs/read_write.c:582
 ksys_write+0x12c/0x228 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589

Allocated by task 10872:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 __svc_create+0x80/0x89c net/sunrpc/svc.c:491
 svc_create_pooled+0x648/0x7d8 net/sunrpc/svc.c:579
 nfsd_create_serv+0x284/0x6a4 fs/nfsd/nfssvc.c:667
 __write_ports_addxprt fs/nfsd/nfsctl.c:750 [inline]
 __write_ports fs/nfsd/nfsctl.c:794 [inline]
 write_ports+0x3e0/0x9f0 fs/nfsd/nfsctl.c:847
 nfsctl_transaction_write+0x114/0x164 fs/nfsd/nfsctl.c:114
 vfs_write+0x2a8/0x7c8 fs/read_write.c:582
 ksys_write+0x12c/0x228 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589

Freed by task 10872:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1735 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1761
 slab_free mm/slub.c:3694 [inline]
 __kmem_cache_free+0xbc/0x21c mm/slub.c:3707
 kfree+0xd0/0x1a8 mm/slab_common.c:988
 svc_destroy+0x144/0x184 net/sunrpc/svc.c:613
 kref_put include/linux/kref.h:65 [inline]
 svc_put include/linux/sunrpc/svc.h:123 [inline]
 __write_ports_addxprt fs/nfsd/nfsctl.c:780 [inline]
 __write_ports fs/nfsd/nfsctl.c:794 [inline]
 write_ports+0x6ec/0x9f0 fs/nfsd/nfsctl.c:847
 nfsctl_transaction_write+0x114/0x164 fs/nfsd/nfsctl.c:114
 vfs_write+0x2a8/0x7c8 fs/read_write.c:582
 ksys_write+0x12c/0x228 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:589

Last potentially related work creation:
 kasan_save_stack+0x40/0x70 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xc0/0xdc mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496
 insert_work+0x64/0x37c kernel/workqueue.c:1361
 __queue_work+0xd00/0x1280 kernel/workqueue.c:1520
 delayed_work_timer_fn+0x74/0x94 kernel/workqueue.c:1646
 call_timer_fn+0x1b8/0x96c kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1747 [inline]
 __run_timers+0x4d0/0x6d8 kernel/time/timer.c:2023
 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:2036
 handle_softirqs+0x318/0xc90 kernel/softirq.c:596
 __do_softirq+0x14/0x20 kernel/softirq.c:630

The buggy address belongs to the object at ffff0000f58f3000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 84 bytes inside of
 512-byte region [ffff0000f58f3000, ffff0000f58f3200)

The buggy address belongs to the physical page:
page:00000000b7222a1e refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1358f0
head:00000000b7222a1e order:2 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000001 ffff0000c0002600
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f58f2f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000f58f2f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000f58f3000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff0000f58f3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000f58f3100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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