kernel BUG in f2fs_write_end_bio

Status: upstream: reported on 2026/09/27 07:00
Subsystems: f2fs
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+eae639926b1c1ac725d5@syzkaller.appspotmail.com
First crash: 4d08h, last: 4d08h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
fe679722 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ kernel BUG in f2fs_write_end_bio 2026/09/26 09:00 2026/09/26 09:00 2026/09/26 10:44 a3c7249d
331200b9 assessment-security 💥 kernel BUG in f2fs_write_end_bio 2026/09/24 11:08 2026/09/24 11:08 2026/09/24 17:04 3c3cdf19
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [f2fs?] kernel BUG in f2fs_write_end_bio 0 (1) 2026/09/27 07:00

Sample crash report:
F2FS-fs (loop0): inconsistent node block, node_type:0, nid:3, node_footer[nid:0,ino:0,ofs:0,cpver:0,blkaddr:0]
------------[ cut here ]------------
kernel BUG at fs/f2fs/data.c:365!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 1055 Comm: kworker/u4:9 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: loop0 loop_workfn
RIP: 0010:f2fs_write_end_bio+0x167d/0x16e0 fs/f2fs/data.c:365
Code: 67 5f 8c e8 75 15 c1 fc 90 0f 0b e8 1d e0 60 fd 48 8b 7c 24 08 48 c7 c6 20 67 5f 8c e8 5c 15 c1 fc 90 0f 0b e8 04 e0 60 fd 90 <0f> 0b e8 fc df 60 fd 48 8b 7c 24 08 48 c7 c6 20 67 5f 8c e8 3b 15
RSP: 0018:ffffc9000527f490 EFLAGS: 00010293
RAX: ffffffff84670d0c RBX: 0000000000000003 RCX: ffff888036980000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: ffffea00010bb900 R08: ffffffff907a767f R09: 1ffffffff20f4ecf
R10: dffffc0000000000 R11: fffffbfff20f4ed0 R12: ffffea00010bb8c0
R13: dffffc0000000000 R14: 0000000000001000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88808c2c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcdf33c4d10 CR3: 000000003b2bb000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 blk_update_request+0x57b/0xe50 block/blk-mq.c:1016
 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1147
 lo_rw_aio_complete drivers/block/loop.c:338 [inline]
 lo_rw_aio+0xcd4/0xf20 drivers/block/loop.c:406
 do_req_filebacked drivers/block/loop.c:430 [inline]
 loop_handle_cmd drivers/block/loop.c:1949 [inline]
 loop_process_work+0x621/0x11c0 drivers/block/loop.c:1984
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:f2fs_write_end_bio+0x167d/0x16e0 fs/f2fs/data.c:365
Code: 67 5f 8c e8 75 15 c1 fc 90 0f 0b e8 1d e0 60 fd 48 8b 7c 24 08 48 c7 c6 20 67 5f 8c e8 5c 15 c1 fc 90 0f 0b e8 04 e0 60 fd 90 <0f> 0b e8 fc df 60 fd 48 8b 7c 24 08 48 c7 c6 20 67 5f 8c e8 3b 15
RSP: 0018:ffffc9000527f490 EFLAGS: 00010293
RAX: ffffffff84670d0c RBX: 0000000000000003 RCX: ffff888036980000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: ffffea00010bb900 R08: ffffffff907a767f R09: 1ffffffff20f4ecf
R10: dffffc0000000000 R11: fffffbfff20f4ed0 R12: ffffea00010bb8c0
R13: dffffc0000000000 R14: 0000000000001000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88808c2c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcdf33c4d10 CR3: 000000001f6d9000 CR4: 0000000000352ef0

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/23 06:57 upstream fe2ec83746e5 abce1216 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root kernel BUG in f2fs_write_end_bio
* Struck through repros no longer work on HEAD.