[moderation] [f2fs?] KASAN: use-after-free Read in f2fs_write_end_io (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9551a26f17d9 Merge tag 'loongarch-6.19' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10471e1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f315601b98a91c0b
dashboard link: https://syzkaller.appspot.com/bug?extid=3a3a2ca2d636b9b07c08
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [ch...@kernel.org jae...@kernel.org linux-f2...@lists.sourceforge.net linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b23c812ec291/disk-9551a26f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8b0564ab1672/vmlinux-9551a26f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b8aac5f6fcdb/bzImage-9551a26f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3a3a2c...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: use-after-free in get_pages fs/f2fs/f2fs.h:2718 [inline]
BUG: KASAN: use-after-free in f2fs_write_end_io+0x9b9/0xb60 fs/f2fs/data.c:364
Read of size 4 at addr ffff8880593896f0 by task kworker/u8:9/1387

CPU: 0 UID: 0 PID: 1387 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: netns cleanup_net
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:200
instrument_atomic_read include/linux/instrumented.h:68 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
get_pages fs/f2fs/f2fs.h:2718 [inline]
f2fs_write_end_io+0x9b9/0xb60 fs/f2fs/data.c:364
blk_update_request+0x57e/0xe60 block/blk-mq.c:1007
blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1169
blk_complete_reqs block/blk-mq.c:1244 [inline]
blk_done_softirq+0x10a/0x160 block/blk-mq.c:1249
handle_softirqs+0x226/0x6d0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
__local_bh_enable_ip+0x1a0/0x2e0 kernel/softirq.c:302
unregister_netdevice_many_notify+0x18f5/0x2330 net/core/dev.c:12391
ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248
cleanup_net+0x4de/0x7b0 net/core/net_namespace.c:696
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x59389
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 0000000000000000 00000000ffffffff 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x40dc0(GFP_KERNEL|__GFP_ZERO|__GFP_COMP), pid 6633, tgid 6632 (syz.3.127), ts 179734786007, free_ts 181834195253
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
prep_new_page mm/page_alloc.c:1854 [inline]
get_page_from_freelist+0x28c0/0x2960 mm/page_alloc.c:3915
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
___kmalloc_large_node+0x4e/0x150 mm/slub.c:5598
__kmalloc_large_noprof+0x1a/0x90 mm/slub.c:5619
kmalloc_noprof include/linux/slab.h:954 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
f2fs_fill_super+0x5a/0x6e30 fs/f2fs/super.c:4895
get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691
vfs_get_tree+0x92/0x2a0 fs/super.c:1751
fc_mount fs/namespace.c:1199 [inline]
do_new_mount_fc fs/namespace.c:3636 [inline]
do_new_mount+0x302/0xa10 fs/namespace.c:3712
do_mount fs/namespace.c:4035 [inline]
__do_sys_mount fs/namespace.c:4224 [inline]
__se_sys_mount+0x313/0x410 fs/namespace.c:4201
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5802 tgid 5802 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1395 [inline]
__free_frozen_pages+0xfe1/0x1170 mm/page_alloc.c:2943
kill_f2fs_super+0x5b6/0x6c0 fs/f2fs/super.c:5458
deactivate_locked_super+0xbc/0x130 fs/super.c:474
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318
task_work_run+0x1d4/0x260 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff888059389580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888059389600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888059389680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888059389700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888059389780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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