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: 6d16h, last: 8h36m
▶ ▼ ✨ 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:
------------[ cut here ]------------
kernel BUG at fs/f2fs/data.c:365!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:f2fs_write_end_bio+0x167d/0x16e0 fs/f2fs/data.c:365
Code: cb be 8b e8 65 cf cb fc 90 0f 0b e8 bd cb 6a fd 48 8b 7c 24 08 48 c7 c6 c0 cb be 8b e8 4c cf cb fc 90 0f 0b e8 a4 cb 6a fd 90 <0f> 0b e8 9c cb 6a fd 48 8b 7c 24 08 48 c7 c6 c0 cb be 8b e8 2b cf
RSP: 0018:ffffc90000147b20 EFLAGS: 00010246
RAX: ffffffff845bf86c RBX: 0000000000000003 RCX: ffff88801cab9f40
RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000100
RBP: ffffea0000cb0b40 R08: 0000000000000100 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1f64570 R12: ffffea0000cb0b00
R13: dffffc0000000000 R14: 0000000000001000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125bc4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb0a51adff8 CR3: 0000000060fca000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 blk_update_request+0x57b/0xe50 block/blk-mq.c:1016
 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1147
 blk_complete_reqs block/blk-mq.c:1222 [inline]
 blk_done_softirq+0x10a/0x160 block/blk-mq.c:1227
 handle_softirqs+0x1da/0x6d0 kernel/softirq.c:645
 run_ksoftirqd+0x53/0x190 kernel/softirq.c:1099
 smpboot_thread_fn+0x565/0xa70 kernel/smpboot.c:160
 kthread+0x38b/0x470 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: cb be 8b e8 65 cf cb fc 90 0f 0b e8 bd cb 6a fd 48 8b 7c 24 08 48 c7 c6 c0 cb be 8b e8 4c cf cb fc 90 0f 0b e8 a4 cb 6a fd 90 <0f> 0b e8 9c cb 6a fd 48 8b 7c 24 08 48 c7 c6 c0 cb be 8b e8 2b cf
RSP: 0018:ffffc90000147b20 EFLAGS: 00010246
RAX: ffffffff845bf86c RBX: 0000000000000003 RCX: ffff88801cab9f40
RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000100
RBP: ffffea0000cb0b40 R08: 0000000000000100 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1f64570 R12: ffffea0000cb0b00
R13: dffffc0000000000 R14: 0000000000001000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125bc4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb0a782b840 CR3: 0000000041172000 CR4: 00000000003526f0

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/29 14:27 upstream 72d3fcf802c4 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in f2fs_write_end_bio
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.