Re: [syzbot] [f2fs?] general protection fault in f2fs_check_opt_consistency

[Chao Yu <chao@kernel.org>]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/chao/linux.git bugfix/syzbot

On 2025/8/16 11:18, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    0e39a731820a Merge tag 'for-6.17-rc1-tag' of git://git.ker..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=13344da2580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=13f39c6a0380a209
> dashboard link: https://syzkaller.appspot.com/bug?extid=d371efea57d5aeab877b
> compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12c22c34580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15a125a2580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/e0297ec5b8e1/disk-0e39a731.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/0396bfd57e65/vmlinux-0e39a731.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/68482d381f43/bzImage-0e39a731.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/f909676ebee0/mount_0.gz
>    fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=15344da2580000)
> 
> The issue was bisected to:
> 
> commit d185351325237da688de006a2c579e82ea97bdfe
> Author: Hongbo Li <lihongbo22@huawei.com>
> Date:   Thu Jul 10 12:14:13 2025 +0000
> 
>      f2fs: separate the options parsing and options checking
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=137ca5a2580000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=10fca5a2580000
> console output: https://syzkaller.appspot.com/x/log.txt?x=177ca5a2580000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+d371efea57d5aeab877b@syzkaller.appspotmail.com
> Fixes: d18535132523 ("f2fs: separate the options parsing and options checking")
> 
> F2FS-fs (loop0): f2fs_recover_fsync_data: recovery fsync data, check_only: 0
> F2FS-fs (loop0): Mounted with checkpoint version = 48b305e4
> Oops: gen[  107.736417][ T5848] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> CPU: 1 UID: 0 PID: 5848 Comm: syz-executor263 Tainted: G        W           6.17.0-rc1-syzkaller-00014-g0e39a731820a #0 PREEMPT_{RT,(full)}
> Tainted: [W]=WARN
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
> RIP: 0010:strcmp+0x3c/0xc0 lib/string.c:284
> Code: 00 fc ff df 45 31 f6 4a 8d 04 37 48 89 c1 48 c1 e9 03 0f b6 0c 19 84 c9 75 2c 42 0f b6 2c 37 4a 8d 04 36 48 89 c1 48 c1 e9 03 <0f> b6 0c 19 84 c9 75 33 42 0f b6 0c 36 40 38 cd 75 48 49 ff c6 40
> RSP: 0018:ffffc90004adf8f8 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
> RDX: 0000000021ec2c00 RSI: 0000000000000000 RDI: ffff888021ec2c80
> RBP: 0000000000000066 R08: 0000000000000000 R09: 0000000000000000
> R10: ffff88803d2c9768 R11: ffffed1007a592fb R12: 1ffff1100611a891
> R13: 0000000000000000 R14: 0000000000000000 R15: ffff888021ec2c80
> FS:  0000555575c20480(0000) GS:ffff8881269c5000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000001000 CR3: 000000003d342000 CR4: 00000000003526f0
> Call Trace:
>   <TASK>
>   f2fs_check_quota_consistency fs/f2fs/super.c:1188 [inline]
>   f2fs_check_opt_consistency+0x1378/0x2c10 fs/f2fs/super.c:1436
>   __f2fs_remount fs/f2fs/super.c:2653 [inline]
>   f2fs_reconfigure+0x482/0x1770 fs/f2fs/super.c:5297
>   reconfigure_super+0x224/0x890 fs/super.c:1077
>   do_remount fs/namespace.c:3314 [inline]
>   path_mount+0xd18/0xfe0 fs/namespace.c:4112
>   do_mount fs/namespace.c:4133 [inline]
>   __do_sys_mount fs/namespace.c:4344 [inline]
>   __se_sys_mount+0x317/0x410 fs/namespace.c:4321
>   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>   entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f13267ca259
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff3d15d4a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f13267ca259
> RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000200000000140 R09: 00007fff3d15d4e0
> R10: 0000000000000020 R11: 0000000000000246 R12: 00007fff3d15d4e0
> R13: 00007fff3d15d768 R14: 431bde82d7b634db R15: 00007f132681303b
>   </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:strcmp+0x3c/0xc0 lib/string.c:284
> Code: 00 fc ff df 45 31 f6 4a 8d 04 37 48 89 c1 48 c1 e9 03 0f b6 0c 19 84 c9 75 2c 42 0f b6 2c 37 4a 8d 04 36 48 89 c1 48 c1 e9 03 <0f> b6 0c 19 84 c9 75 33 42 0f b6 0c 36 40 38 cd 75 48 49 ff c6 40
> RSP: 0018:ffffc90004adf8f8 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
> RDX: 0000000021ec2c00 RSI: 0000000000000000 RDI: ffff888021ec2c80
> RBP: 0000000000000066 R08: 0000000000000000 R09: 0000000000000000
> R10: ffff88803d2c9768 R11: ffffed1007a592fb R12: 1ffff1100611a891
> R13: 0000000000000000 R14: 0000000000000000 R15: ffff888021ec2c80
> FS:  0000555575c20480(0000) GS:ffff8881268c5000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000003d342000 CR4: 00000000003526f0
> ----------------
> Code disassembly (best guess), 4 bytes skipped:
>     0:	45 31 f6             	xor    %r14d,%r14d
>     3:	4a 8d 04 37          	lea    (%rdi,%r14,1),%rax
>     7:	48 89 c1             	mov    %rax,%rcx
>     a:	48 c1 e9 03          	shr    $0x3,%rcx
>     e:	0f b6 0c 19          	movzbl (%rcx,%rbx,1),%ecx
>    12:	84 c9                	test   %cl,%cl
>    14:	75 2c                	jne    0x42
>    16:	42 0f b6 2c 37       	movzbl (%rdi,%r14,1),%ebp
>    1b:	4a 8d 04 36          	lea    (%rsi,%r14,1),%rax
>    1f:	48 89 c1             	mov    %rax,%rcx
>    22:	48 c1 e9 03          	shr    $0x3,%rcx
> * 26:	0f b6 0c 19          	movzbl (%rcx,%rbx,1),%ecx <-- trapping instruction
>    2a:	84 c9                	test   %cl,%cl
>    2c:	75 33                	jne    0x61
>    2e:	42 0f b6 0c 36       	movzbl (%rsi,%r14,1),%ecx
>    33:	40 38 cd             	cmp    %cl,%bpl
>    36:	75 48                	jne    0x80
>    38:	49 ff c6             	inc    %r14
>    3b:	40                   	rex
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
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> 
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> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
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> 
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