linux-kernel - Re: [PATCH v8 1/1] smb: move FILE_SYSTEM_ATTRIBUTE

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Message-ID: <a7ae1b5f-255a-40cb-96da-6f8495d4b7b3@kylinos.cn>
Date: Mon, 17 Nov 2025 09:04:48 +0800
From: ChenXiaoSong <chenxiaosong@...inos.cn>
To: Namjae Jeon <linkinjeon@...nel.org>, chenxiaosong.chenxiaosong@...ux.dev
Cc: sfrench@...ba.org, smfrench@...il.com, linkinjeon@...ba.org,
 christophe.jaillet@...adoo.fr, linux-cifs@...r.kernel.org,
 linux-kernel@...r.kernel.org, chenxiaosong@...nxiaosong.com
Subject: Re: [PATCH v8 1/1] smb: move FILE_SYSTEM_ATTRIBUTE_INFO to
 common/fscc.h

Hi Namjae,

I have confirmed that when FileSystemName uses flexible array member, 
fsAttrInfo in struct cifs_tcon does not include FileSystemName.

The following part in the CIFSSMBQFSAttributeInfo() function is correct, 
we cannot add MAX_FS_NAME_LEN to sizeof(FILE_SYSTEM_ATTRIBUTE_INFO).

```c
CIFSSMBQFSAttributeInfo()
{
...
	memcpy(&tcon->fsAttrInfo, response_data,
		sizeof(FILE_SYSTEM_ATTRIBUTE_INFO)); // it's correct here
...
}
```

And in the following part of the SMB2_QFS_attr() function, we should 
change it to `memcpy(..., min_t(..., min_len))`.

```c
SMB2_QFS_attr()
{
...
     if (level == FS_ATTRIBUTE_INFORMATION)
             memcpy(&tcon->fsAttrInfo, offset
                     + (char *)rsp, min_t(unsigned int,
                     rsp_len, max_len)); // should use `min_len` here
...
}
```

Thanks,
ChenXiaoSong.

On 11/17/25 07:00, Namjae Jeon wrote:
> On Sun, Nov 16, 2025 at 3:53 PM <chenxiaosong.chenxiaosong@...ux.dev> wrote:
>>
>> From: ChenXiaoSong <chenxiaosong@...inos.cn>
>>
>> Modify the following places:
>>
>>    - struct filesystem_attribute_info -> FILE_SYSTEM_ATTRIBUTE_INFO
>>    - Remove MIN_FS_ATTR_INFO_SIZE definition
>>    - Introduce MAX_FS_NAME_LEN
>>    - max_len of FileFsAttributeInformation -> sizeof(FILE_SYSTEM_ATTRIBUTE_INFO) + MAX_FS_NAME_LEN
>>    - min_len of FileFsAttributeInformation -> sizeof(FILE_SYSTEM_ATTRIBUTE_INFO)
>>
>> Then move FILE_SYSTEM_ATTRIBUTE_INFO to common header file.
>>
>> Suggested-by: Namjae Jeon <linkinjeon@...nel.org>
>> Signed-off-by: ChenXiaoSong <chenxiaosong@...inos.cn>
> 
> Did you check if it is being used here too?
> cifssmb.c:4866:        sizeof(FILE_SYSTEM_ATTRIBUTE_INFO));