syzbot

==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: use-after-free in atomic_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:705 [inline]
BUG: KASAN: use-after-free in queued_spin_lock include/asm-generic/qspinlock.h:82 [inline]
BUG: KASAN: use-after-free in do_raw_spin_lock_flags include/linux/spinlock.h:196 [inline]
BUG: KASAN: use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [inline]
BUG: KASAN: use-after-free in _raw_spin_lock_irqsave+0xb5/0x130 kernel/locking/spinlock.c:159
Write of size 4 at addr ffff888121a66038 by task f2fs_discard-7:/3792

CPU: 1 PID: 3792 Comm: f2fs_discard-7: Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:705 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:82 [inline]
 do_raw_spin_lock_flags include/linux/spinlock.h:196 [inline]
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irqsave+0xb5/0x130 kernel/locking/spinlock.c:159
 prepare_to_wait_event+0x2a/0x410 kernel/sched/wait.c:296
 issue_discard_thread+0x7a9/0x1360 fs/f2fs/segment.c:1815
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

Allocated by task 3486:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 __kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:463
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x162/0x2d0 mm/slub.c:2965
 getname_flags+0xb9/0x500 fs/namei.c:141
 user_path_at_empty+0x2f/0x50 fs/namei.c:2748
 user_path_at include/linux/namei.h:60 [inline]
 ksys_umount fs/namespace.c:1768 [inline]
 __do_sys_umount fs/namespace.c:1776 [inline]
 __se_sys_umount fs/namespace.c:1774 [inline]
 __x64_sys_umount+0xf9/0x170 fs/namespace.c:1774
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 3486:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kmem_cache_free+0x100/0x2d0 mm/slub.c:3224
 putname fs/namei.c:262 [inline]
 filename_lookup+0x4b3/0x6a0 fs/namei.c:2478
 user_path_at_empty+0x43/0x50 fs/namei.c:2748
 user_path_at include/linux/namei.h:60 [inline]
 ksys_umount fs/namespace.c:1768 [inline]
 __do_sys_umount fs/namespace.c:1776 [inline]
 __se_sys_umount fs/namespace.c:1774 [inline]
 __x64_sys_umount+0xf9/0x170 fs/namespace.c:1774
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff888121a65500
 which belongs to the cache names_cache of size 4096
The buggy address is located 2872 bytes inside of
 4096-byte region [ffff888121a65500, ffff888121a66500)
The buggy address belongs to the page:
page:ffffea0004869800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x121a60
head:ffffea0004869800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff88810018bb00
raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 3745, ts 221698470690, free_ts 219934393609
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2a6/0x450 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x1ac/0x2d0 mm/slub.c:2965
 getname_flags+0xb9/0x500 fs/namei.c:141
 getname+0x19/0x20 fs/namei.c:212
 do_sys_openat2+0xde/0x750 fs/open.c:1213
 do_sys_open fs/open.c:1235 [inline]
 __do_sys_openat fs/open.c:1251 [inline]
 __se_sys_openat fs/open.c:1246 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1246
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page mm/page_alloc.c:3391 [inline]
 free_the_page mm/page_alloc.c:5443 [inline]
 __free_pages+0x146/0x3b0 mm/page_alloc.c:5454
 __vunmap+0x86d/0x9f0 mm/vmalloc.c:2307
 __vfree mm/vmalloc.c:2356 [inline]
 vfree+0x61/0x90 mm/vmalloc.c:2387
 kcov_mmap+0x8f/0x130 kernel/kcov.c:489
 call_mmap include/linux/fs.h:2071 [inline]
 mmap_file+0x60/0xb0 mm/util.c:1085
 __mmap_region mm/mmap.c:1884 [inline]
 mmap_region+0x10be/0x18d0 mm/mmap.c:3075
 do_mmap+0x801/0xeb0 mm/mmap.c:1661
 vm_mmap_pgoff+0x211/0x370 mm/util.c:543
 ksys_mmap_pgoff+0x16f/0x1e0 mm/mmap.c:1712
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:95 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
 __x64_sys_mmap+0xfa/0x110 arch/x86/kernel/sys_x86_64.c:86
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff888121a65f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888121a65f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888121a66000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff888121a66080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888121a66100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
list_del corruption. prev->next should be ffffc90001dcfe58, but was 0000000000000000
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:61!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 3792 Comm: f2fs_discard-7: Tainted: G    B   W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__list_del_entry_valid+0x10c/0x120 lib/list_debug.c:59
Code: 48 89 de e8 a6 a2 38 02 0f 0b 48 c7 c7 60 86 40 85 48 89 de e8 95 a2 38 02 0f 0b 48 c7 c7 c0 86 40 85 48 89 de e8 84 a2 38 02 <0f> 0b 48 c7 c7 20 87 40 85 48 89 de e8 73 a2 38 02 0f 0b 00 55 48
RSP: 0018:ffffc90001dcfc80 EFLAGS: 00010046
RAX: 0000000000000054 RBX: ffffc90001dcfe58 RCX: d6dac33799a19100
RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
RBP: ffffc90001dcfca0 R08: ffff8881f7052fbf R09: 1ffff1103ee0a5f7
R10: dffffc0000000000 R11: ffffed103ee0a5f8 R12: dffffc0000000000
R13: ffff888121a66038 R14: ffff888121a66040 R15: ffff888121a66040
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdc9977cff8 CR3: 0000000138115000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __list_del_entry include/linux/list.h:132 [inline]
 list_del_init include/linux/list.h:204 [inline]
 finish_wait+0xb0/0x190 kernel/sched/wait.c:397
 issue_discard_thread+0x8a3/0x1360 fs/f2fs/segment.c:1815
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Modules linked in:
---[ end trace 11fa03bd2ff5b042 ]---
RIP: 0010:__list_del_entry_valid+0x10c/0x120 lib/list_debug.c:59
Code: 48 89 de e8 a6 a2 38 02 0f 0b 48 c7 c7 60 86 40 85 48 89 de e8 95 a2 38 02 0f 0b 48 c7 c7 c0 86 40 85 48 89 de e8 84 a2 38 02 <0f> 0b 48 c7 c7 20 87 40 85 48 89 de e8 73 a2 38 02 0f 0b 00 55 48
RSP: 0018:ffffc90001dcfc80 EFLAGS: 00010046
RAX: 0000000000000054 RBX: ffffc90001dcfe58 RCX: d6dac33799a19100
RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
RBP: ffffc90001dcfca0 R08: ffff8881f7052fbf R09: 1ffff1103ee0a5f7
R10: dffffc0000000000 R11: ffffed103ee0a5f8 R12: dffffc0000000000
R13: ffff888121a66038 R14: ffff888121a66040 R15: ffff888121a66040
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdc9977cff8 CR3: 0000000138115000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400