================================================================== 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 ffff888027ff8850 by task syz-executor/4278 CPU: 0 PID: 4278 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+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:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f4cfa19f0d7 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:00007ffd6ed53518 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f4cfa23330a RCX: 00007f4cfa19f0d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd6ed535d0 RBP: 00007ffd6ed535d0 R08: 00007ffd6ed545d0 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd6ed54660 R13: 00007f4cfa23330a R14: 0000000000014998 R15: 00007ffd6ed546a0 Allocated by task 4491: 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:464 svc_create_pooled+0x71f/0x8c0 net/sunrpc/svc.c:552 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 4491: 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 The buggy address belongs to the object at ffff888027ff8800 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 80 bytes inside of 512-byte region [ffff888027ff8800, ffff888027ff8a00) The buggy address belongs to the physical page: page:ffffea00009ffe00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27ff8 head:ffffea00009ffe00 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 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 11698264313, free_ts 0 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_page_interleave+0x24/0x1e0 mm/mempolicy.c:2115 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] usb_cache_string+0x62/0x130 drivers/usb/core/message.c:1085 usb_enumerate_device drivers/usb/core/hub.c:2501 [inline] usb_new_device+0x278/0x15e0 drivers/usb/core/hub.c:2629 register_root_hub+0x258/0x550 drivers/usb/core/hcd.c:1019 usb_add_hcd+0xbb9/0x1080 drivers/usb/core/hcd.c:2999 dummy_hcd_probe+0x130/0x260 drivers/usb/gadget/udc/dummy_hcd.c:2709 platform_probe+0x137/0x1c0 drivers/base/platform.c:1400 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x24a/0xb40 drivers/base/dd.c:638 page_owner free stack trace missing Memory state around the buggy address: ffff888027ff8700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888027ff8780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888027ff8800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888027ff8880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888027ff8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================