* [syzbot ci] Re: exfat: unify FAT chain walking helpers
[not found] <20260331091113.20882-1-chizhiling@163.com>
@ 2026-03-31 15:27 ` syzbot ci
2026-04-01 2:45 ` Chi Zhiling
0 siblings, 1 reply; 2+ messages in thread
From: syzbot ci @ 2026-03-31 15:27 UTC (permalink / raw)
To: chizhiling, chizhiling, linkinjeon, linux-fsdevel, linux-kernel,
sj1557.seo, yuezhang.mo
Cc: syzbot, syzkaller-bugs
syzbot ci has tested the following series
[v1] exfat: unify FAT chain walking helpers
https://lore.kernel.org/all/20260331091113.20882-1-chizhiling@163.com
* [PATCH v1 1/6] exfat: fix incorrect directory checksum after rename to shorter name
* [PATCH v1 2/6] exfat: introduce exfat_fat_walk helper
* [PATCH v1 3/6] exfat: use exfat_fat_walk helper to simplify fat entry walking
* [PATCH v1 4/6] exfat: remove NULL cache pointer case in exfat_ent_get
* [PATCH v1 5/6] exfat: introduce exfat_chain_advance helper
* [PATCH v1 6/6] exfat: use exfat_chain_advance helper
and found the following issue:
WARNING in exfat_find_empty_entry
Full report is available here:
https://ci.syzbot.org/series/d9d5a999-e11a-43e1-ac76-9c718e136f25
***
WARNING in exfat_find_empty_entry
tree: linux-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next
base: d1d75eaf01abceb3d5cb50253375b5f254b6be54
arch: amd64
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config: https://ci.syzbot.org/builds/177ab8e9-7eef-44cc-8b1d-6e8e2b44adaf/config
C repro: https://ci.syzbot.org/findings/9b0e35b9-b5be-440e-9461-2f19c03cb16a/c_repro
syz repro: https://ci.syzbot.org/findings/9b0e35b9-b5be-440e-9461-2f19c03cb16a/syz_repro
exFAT-fs (loop0): start_clu is invalid cluster(0xffffffff)
exFAT-fs (loop0): valid_size(150994954) is greater than size(10)
------------[ cut here ]------------
chain->dir != EXFAT_EOF_CLUSTER
WARNING: fs/exfat/exfat_fs.h:575 at exfat_chain_advance fs/exfat/exfat_fs.h:575 [inline], CPU#0: syz.0.17/5981
WARNING: fs/exfat/exfat_fs.h:575 at exfat_search_empty_slot fs/exfat/namei.c:249 [inline], CPU#0: syz.0.17/5981
WARNING: fs/exfat/exfat_fs.h:575 at exfat_find_empty_entry+0x754/0x13b0 fs/exfat/namei.c:318, CPU#0: syz.0.17/5981
Modules linked in:
CPU: 0 UID: 0 PID: 5981 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:exfat_chain_advance fs/exfat/exfat_fs.h:575 [inline]
RIP: 0010:exfat_search_empty_slot fs/exfat/namei.c:249 [inline]
RIP: 0010:exfat_find_empty_entry+0x754/0x13b0 fs/exfat/namei.c:318
Code: 00 bf ff ff ff ff 44 89 e6 e8 18 56 1f ff 41 83 fc ff 75 10 e8 cd 51 1f ff 45 29 ee 0f 8d ad fe ff ff eb 12 e8 bd 51 1f ff 90 <0f> 0b 90 45 29 ee 0f 8d 99 fe ff ff e8 ab 51 1f ff 41 01 df 48 8b
RSP: 0018:ffffc9000499f340 EFLAGS: 00010293
RAX: ffffffff82a639c3 RBX: 0000000000000020 RCX: ffff88816d588000
RDX: 0000000000000000 RSI: 000000000000000b RDI: 00000000ffffffff
RBP: ffffc9000499f570 R08: ffff888119e14a5b R09: 1ffff110233c294b
R10: dffffc0000000000 R11: ffffed10233c294c R12: 000000000000000b
R13: 0000000000000080 R14: 0000000000000000 R15: 0000000000000060
FS: 000055557e214500(0000) GS:ffff88818de66000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000006200 CR3: 00000001bcf7c000 CR4: 00000000000006f0
Call Trace:
<TASK>
exfat_rename_file fs/exfat/namei.c:1025 [inline]
__exfat_rename fs/exfat/namei.c:1177 [inline]
exfat_rename+0xb49/0x1f90 fs/exfat/namei.c:1251
vfs_rename+0xa96/0xeb0 fs/namei.c:6026
filename_renameat2+0x539/0x9c0 fs/namei.c:6144
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0x55/0x2c0 fs/namei.c:6184
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f66f1b9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcad04e2e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f66f1e15fa0 RCX: 00007f66f1b9c819
RDX: 0000000000000000 RSI: 0000200000000400 RDI: 0000200000006200
RBP: 00007f66f1c32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f66f1e15fac R14: 00007f66f1e15fa0 R15: 00007f66f1e15fa0
</TASK>
***
If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syzbot@syzkaller.appspotmail.com
---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.
To test a patch for this bug, please reply with `#syz test`
(should be on a separate line).
The patch should be attached to the email.
Note: arguments like custom git repos and branches are not supported.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [syzbot ci] Re: exfat: unify FAT chain walking helpers
2026-03-31 15:27 ` [syzbot ci] Re: exfat: unify FAT chain walking helpers syzbot ci
@ 2026-04-01 2:45 ` Chi Zhiling
0 siblings, 0 replies; 2+ messages in thread
From: Chi Zhiling @ 2026-04-01 2:45 UTC (permalink / raw)
To: syzbot ci, chizhiling, linkinjeon, linux-fsdevel, linux-kernel,
sj1557.seo, yuezhang.mo
Cc: syzbot, syzkaller-bugs
On 3/31/26 11:27 PM, syzbot ci wrote:
> syzbot ci has tested the following series
>
> [v1] exfat: unify FAT chain walking helpers
> https://lore.kernel.org/all/20260331091113.20882-1-chizhiling@163.com
> * [PATCH v1 1/6] exfat: fix incorrect directory checksum after rename to shorter name
> * [PATCH v1 2/6] exfat: introduce exfat_fat_walk helper
> * [PATCH v1 3/6] exfat: use exfat_fat_walk helper to simplify fat entry walking
> * [PATCH v1 4/6] exfat: remove NULL cache pointer case in exfat_ent_get
> * [PATCH v1 5/6] exfat: introduce exfat_chain_advance helper
> * [PATCH v1 6/6] exfat: use exfat_chain_advance helper
>
> and found the following issue:
> WARNING in exfat_find_empty_entry
>
> Full report is available here:
> https://ci.syzbot.org/series/d9d5a999-e11a-43e1-ac76-9c718e136f25
>
> ***
>
> WARNING in exfat_find_empty_entry
>
> tree: linux-next
> URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next
> base: d1d75eaf01abceb3d5cb50253375b5f254b6be54
> arch: amd64
> compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config: https://ci.syzbot.org/builds/177ab8e9-7eef-44cc-8b1d-6e8e2b44adaf/config
> C repro: https://ci.syzbot.org/findings/9b0e35b9-b5be-440e-9461-2f19c03cb16a/c_repro
> syz repro: https://ci.syzbot.org/findings/9b0e35b9-b5be-440e-9461-2f19c03cb16a/syz_repro
>
> exFAT-fs (loop0): start_clu is invalid cluster(0xffffffff)
> exFAT-fs (loop0): valid_size(150994954) is greater than size(10)
> ------------[ cut here ]------------
> chain->dir != EXFAT_EOF_CLUSTER
> WARNING: fs/exfat/exfat_fs.h:575 at exfat_chain_advance fs/exfat/exfat_fs.h:575 [inline], CPU#0: syz.0.17/5981
> WARNING: fs/exfat/exfat_fs.h:575 at exfat_search_empty_slot fs/exfat/namei.c:249 [inline], CPU#0: syz.0.17/5981
> WARNING: fs/exfat/exfat_fs.h:575 at exfat_find_empty_entry+0x754/0x13b0 fs/exfat/namei.c:318, CPU#0: syz.0.17/5981
> Modules linked in:
> CPU: 0 UID: 0 PID: 5981 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:exfat_chain_advance fs/exfat/exfat_fs.h:575 [inline]
> RIP: 0010:exfat_search_empty_slot fs/exfat/namei.c:249 [inline]
> RIP: 0010:exfat_find_empty_entry+0x754/0x13b0 fs/exfat/namei.c:318
> Code: 00 bf ff ff ff ff 44 89 e6 e8 18 56 1f ff 41 83 fc ff 75 10 e8 cd 51 1f ff 45 29 ee 0f 8d ad fe ff ff eb 12 e8 bd 51 1f ff 90 <0f> 0b 90 45 29 ee 0f 8d 99 fe ff ff e8 ab 51 1f ff 41 01 df 48 8b
> RSP: 0018:ffffc9000499f340 EFLAGS: 00010293
> RAX: ffffffff82a639c3 RBX: 0000000000000020 RCX: ffff88816d588000
> RDX: 0000000000000000 RSI: 000000000000000b RDI: 00000000ffffffff
> RBP: ffffc9000499f570 R08: ffff888119e14a5b R09: 1ffff110233c294b
> R10: dffffc0000000000 R11: ffffed10233c294c R12: 000000000000000b
> R13: 0000000000000080 R14: 0000000000000000 R15: 0000000000000060
> FS: 000055557e214500(0000) GS:ffff88818de66000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000006200 CR3: 00000001bcf7c000 CR4: 00000000000006f0
> Call Trace:
> <TASK>
> exfat_rename_file fs/exfat/namei.c:1025 [inline]
> __exfat_rename fs/exfat/namei.c:1177 [inline]
> exfat_rename+0xb49/0x1f90 fs/exfat/namei.c:1251
> vfs_rename+0xa96/0xeb0 fs/namei.c:6026
> filename_renameat2+0x539/0x9c0 fs/namei.c:6144
> __do_sys_rename fs/namei.c:6188 [inline]
> __se_sys_rename+0x55/0x2c0 fs/namei.c:6184
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f66f1b9c819
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffcad04e2e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
> RAX: ffffffffffffffda RBX: 00007f66f1e15fa0 RCX: 00007f66f1b9c819
> RDX: 0000000000000000 RSI: 0000200000000400 RDI: 0000200000006200
> RBP: 00007f66f1c32c91 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f66f1e15fac R14: 00007f66f1e15fa0 R15: 00007f66f1e15fa0
> </TASK>
It looks like I should remove this WARN_ON_ONCE statement. This check is
not reasonable when accessing directories, and I will fix it in v2.
Thanks,
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
> Tested-by: syzbot@syzkaller.appspotmail.com
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at syzkaller@googlegroups.com.
>
> To test a patch for this bug, please reply with `#syz test`
> (should be on a separate line).
>
> The patch should be attached to the email.
> Note: arguments like custom git repos and branches are not supported.
^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] <20260331091113.20882-1-chizhiling@163.com>
2026-03-31 15:27 ` [syzbot ci] Re: exfat: unify FAT chain walking helpers syzbot ci
2026-04-01 2:45 ` Chi Zhiling
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