[syzbot] [f2fs?] general protection fault in new_curseg
From: syzbot
Date: Tue Sep 01 2026 - 23:41:49 EST
Hello,
syzbot found the following issue on:
HEAD commit: 89a312991dc6 Merge tag 'cifs-fixes-7.3-rc2' of https://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1075e779580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e909ffe6b35dddb7
dashboard link: https://syzkaller.appspot.com/bug?extid=ae5b8eb92ed40411ce16
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-89a31299.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/114a4744ab8e/vmlinux-89a31299.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c65021627f2c/bzImage-89a31299.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ae5b8eb92ed40411ce16@xxxxxxxxxxxxxxxxxxxxxxxxx
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 0 UID: 0 PID: 12 Comm: kworker/u4:0 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: writeback wb_workfn (flush-7:0)
RIP: 0010:f2fs_dev_is_alloc_blocked fs/f2fs/segment.h:956 [inline]
RIP: 0010:get_new_segment fs/f2fs/segment.c:2964 [inline]
RIP: 0010:new_curseg+0x1134/0x3580 fs/f2fs/segment.c:3110
Code: e8 21 ab ce fd 48 8b 7c 24 30 48 8b 07 49 6b cf 70 4c 8d 34 08 49 83 c6 61 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 73 11 00 00 41 80 3e 00 0f 84 e6 00 00 00
RSP: 0018:ffffc9000025e628 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000008000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000008000 RDI: ffff888012125a88
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200004bcb4 R12: ffff888052be0000
R13: 0000000000000004 R14: 0000000000000061 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88808c2cf000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200001000000 CR3: 000000004fe72000 CR4: 0000000000352ef0
Call Trace:
<TASK>
f2fs_allocate_data_block+0x229c/0x43c0 fs/f2fs/segment.c:3979
do_write_page+0x13f/0x880 fs/f2fs/segment.c:4099
f2fs_outplace_write_data+0x11a/0x220 fs/f2fs/segment.c:4175
f2fs_write_compressed_pages fs/f2fs/compress.c:1403 [inline]
f2fs_write_multi_pages+0x43bb/0x6370 fs/f2fs/compress.c:1602
f2fs_write_cache_pages fs/f2fs/data.c:3351 [inline]
__f2fs_write_data_pages fs/f2fs/data.c:3603 [inline]
f2fs_write_data_pages+0x19bb/0x36f0 fs/f2fs/data.c:3641
do_writepages+0x338/0x560 mm/page-writeback.c:2560
__writeback_single_inode+0x136/0x1220 fs/fs-writeback.c:1788
writeback_sb_inodes+0x9de/0x1b00 fs/fs-writeback.c:2099
__writeback_inodes_wb+0x114/0x240 fs/fs-writeback.c:2175
wb_writeback+0x42f/0xad0 fs/fs-writeback.c:2286
wb_check_start_all fs/fs-writeback.c:2412 [inline]
wb_do_writeback fs/fs-writeback.c:2459 [inline]
wb_workfn+0x980/0x10f0 fs/fs-writeback.c:2497
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_dev_is_alloc_blocked fs/f2fs/segment.h:956 [inline]
RIP: 0010:get_new_segment fs/f2fs/segment.c:2964 [inline]
RIP: 0010:new_curseg+0x1134/0x3580 fs/f2fs/segment.c:3110
Code: e8 21 ab ce fd 48 8b 7c 24 30 48 8b 07 49 6b cf 70 4c 8d 34 08 49 83 c6 61 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 73 11 00 00 41 80 3e 00 0f 84 e6 00 00 00
RSP: 0018:ffffc9000025e628 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000008000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000008000 RDI: ffff888012125a88
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200004bcb4 R12: ffff888052be0000
R13: 0000000000000004 R14: 0000000000000061 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88808c2cf000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200001000000 CR3: 000000004fe72000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
0: e8 21 ab ce fd call 0xfdceab26
5: 48 8b 7c 24 30 mov 0x30(%rsp),%rdi
a: 48 8b 07 mov (%rdi),%rax
d: 49 6b cf 70 imul $0x70,%r15,%rcx
11: 4c 8d 34 08 lea (%rax,%rcx,1),%r14
15: 49 83 c6 61 add $0x61,%r14
19: 4c 89 f0 mov %r14,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 0f b6 04 08 movzbl (%rax,%rcx,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 0f 85 73 11 00 00 jne 0x11a9
36: 41 80 3e 00 cmpb $0x0,(%r14)
3a: 0f 84 e6 00 00 00 je 0x126
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup