[v6.6] KASAN: slab-use-after-free Read in f2fs_commit_super

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c596736dadab Linux 6.6.120
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17354052580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=b31e7b586d20ff61b581
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10b54052580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111095fa580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/855c94eb3eef/disk-c596736d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b7510b30b774/vmlinux-c596736d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3ce7fe4f6991/bzImage-c596736d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/5613667b1e3c/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=1744799a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b31e7b...@syzkaller.appspotmail.com

==================================================================
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
==================================================================


---
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