KASAN: slab-use-after-free Read in f2fs_commit_super

Status: upstream: reported C repro on 2026/01/13 11:34
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+b31e7b586d20ff61b581@syzkaller.appspotmail.com
First crash: 223d, last: 131d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/02/04 linux-6.6.y (ToT) 2cf6f68313dc C [report] KASAN: slab-use-after-free Read in f2fs_record_error_work
2026/01/21 upstream (ToT) 6c790212c588 C Didn't crash
▶ ▼ Fix bisection attempts (4)
Created Duration User Patch Repo Result
2026/05/29 05:18 39m fix candidate upstream error job log
2026/04/06 06:19 1m fix candidate upstream error job log
2026/03/06 22:17 1m fix candidate upstream error job log
2026/02/04 21:12 1m fix candidate upstream error job log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in f2fs_commit_super+0x761/0x990 fs/f2fs/super.c:4027
Read of size 8 at addr ffff888079628000 by task kworker/1:3/5847

CPU: 1 PID: 5847 Comm: kworker/1:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events f2fs_record_error_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 f2fs_commit_super+0x761/0x990 fs/f2fs/super.c:4027
 f2fs_record_stop_reason fs/f2fs/super.c:4062 [inline]
 f2fs_record_error_work+0x138/0x1d0 fs/f2fs/super.c:4160
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 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
 </TASK>

Allocated by task 5934:
 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]
 f2fs_fill_super+0xc9/0x6cc0 fs/f2fs/super.c:4341
 mount_bdev+0x22b/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
 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 5934:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 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+0x130/0x1b0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
 f2fs_fill_super+0x3dad/0x6cc0 fs/f2fs/super.c:4809
 mount_bdev+0x22b/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
 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:1651
 __queue_work+0xc39/0x1020 kernel/workqueue.c:1800
 queue_work_on+0x121/0x1e0 kernel/workqueue.c:1835
 f2fs_submit_page_bio+0x1c3/0x650 fs/f2fs/data.c:694
 __get_meta_page+0x18f/0x580 fs/f2fs/checkpoint.c:87
 f2fs_get_meta_page fs/f2fs/checkpoint.c:112 [inline]
 get_checkpoint_version+0x3c/0x330 fs/f2fs/checkpoint.c:851
 validate_checkpoint+0x153/0x250 fs/f2fs/checkpoint.c:900
 f2fs_get_valid_checkpoint+0x25e/0x940 fs/f2fs/checkpoint.c:939
 f2fs_fill_super+0x3f3d/0x6cc0 fs/f2fs/super.c:4478
 mount_bdev+0x22b/0x2d0 fs/super.c:1643
 legacy_get_tree+0xea/0x180 fs/fs_context.c:662
 vfs_get_tree+0x8c/0x280 fs/super.c:1764
 do_new_mount+0x24b/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3912
 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

The buggy address belongs to the object at ffff888079628000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 0 bytes inside of
 freed 8192-byte region [ffff888079628000, ffff88807962a000)

The buggy address belongs to the physical page:
page:ffffea0001e58a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x79628
head:ffffea0001e58a00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017842280 0000000000000000 dead000000000001
raw: 0000000000000000 0000000080020002 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5422, tgid 5422 (rcS), ts 57006534569, free_ts 57006162108
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2081
 ___slab_alloc+0xc6d/0x1300 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+0x1a2/0x260 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]
 tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
 tomoyo_init_log+0x1104/0x1f10 security/tomoyo/audit.c:264
 tomoyo_supervisor+0x32d/0x1080 security/tomoyo/common.c:2089
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x14a/0x1e0 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0x1594/0x1a60 security/tomoyo/domain.c:881
 tomoyo_bprm_check_security+0x116/0x170 security/tomoyo/tomoyo.c:101
 security_bprm_check+0x62/0xa0 security/security.c:1103
 search_binary_handler fs/exec.c:1763 [inline]
 exec_binprm fs/exec.c:1817 [inline]
 bprm_execve+0xa51/0x16f0 fs/exec.c:1892
 do_execveat_common+0x51b/0x6c0 fs/exec.c:1998
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x31d/0x410 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa4/0x240 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 tomoyo_add_entry security/tomoyo/common.c:2023 [inline]
 tomoyo_supervisor+0xb70/0x1080 security/tomoyo/common.c:2095
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x14a/0x1e0 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0x1594/0x1a60 security/tomoyo/domain.c:881
 tomoyo_bprm_check_security+0x116/0x170 security/tomoyo/tomoyo.c:101
 security_bprm_check+0x62/0xa0 security/security.c:1103

Memory state around the buggy address:
 ffff888079627f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888079627f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888079628000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888079628080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888079628100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/13 11:34 linux-6.6.y c596736dadab d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/04/15 11:17 linux-6.6.y 8cee53b8eaeb c441f497 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/03/04 11:35 linux-6.6.y 7a137e9bfa0e e6b6b96b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/25 10:59 linux-6.6.y 7a137e9bfa0e 94a9671e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/19 18:00 linux-6.6.y 7a137e9bfa0e c8d8c52d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/19 03:49 linux-6.6.y 56865d9b7074 746545b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/16 14:36 linux-6.6.y ae462074fde3 5d52cba5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/05 21:50 linux-6.6.y 2cf6f68313dc f03c4191 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/02 21:12 linux-6.6.y 2cf6f68313dc d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/02 21:11 linux-6.6.y 2cf6f68313dc d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/02/02 08:52 linux-6.6.y 2cf6f68313dc 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/01/29 23:43 linux-6.6.y cbb31f77b879 bfa73b7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/01/27 10:26 linux-6.6.y cbb31f77b879 9a514c2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/01/26 22:40 linux-6.6.y cbb31f77b879 efb3e894 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
2026/01/23 09:50 linux-6.6.y cbb31f77b879 e2b1b6e6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in f2fs_commit_super
* Struck through repros no longer work on HEAD.