Re: [regression 6.1.80+] "CIFS: VFS: directory entry name would overflow frame end of buf" and invisible files under certain conditions and at least with noserverino mount option

[Paulo Alcantara <pc@manguebit.com>]

Salvatore Bonaccorso <carnil@debian.org> writes:

> On Wed, Apr 17, 2024 at 07:58:56PM -0300, Paulo Alcantara wrote:
>> Hi Salvatore,
>> 
>> Salvatore Bonaccorso <carnil@debian.org> writes:
>> 
>> > In Debian we got two reports of cifs mounts not functioning, hiding
>> > certain files. The two reports are:
>> >
>> > https://bugs.debian.org/1069102
>> > https://bugs.debian.org/1069092
>> >
>> > On those cases kernel logs error
>> >
>> > [   23.225952] CIFS: VFS: directory entry name would overflow frame end of buf 00000000a44b272c
>> 
>> I couldn't reproduce it.  Does the following fix your issue:
>> 
>> diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
>> index 4c1231496a72..3ee35430595e 100644
>> --- a/fs/smb/client/smb2pdu.c
>> +++ b/fs/smb/client/smb2pdu.c
>> @@ -5083,7 +5083,7 @@ smb2_parse_query_directory(struct cifs_tcon *tcon,
>>  		info_buf_size = sizeof(struct smb2_posix_info);
>>  		break;
>>  	case SMB_FIND_FILE_FULL_DIRECTORY_INFO:
>> -		info_buf_size = sizeof(FILE_FULL_DIRECTORY_INFO);
>> +		info_buf_size = sizeof(FILE_FULL_DIRECTORY_INFO) - 1;
>>  		break;
>>  	default:
>>  		cifs_tcon_dbg(VFS, "info level %u isn't supported\n",
>> 
>> If not, please provide network trace and verbose logs.
>
> Yes that appears to fix the issue.

Thanks for quickly testing it.  So the above change indicates that we're
missing 35235e19b393 ("cifs: Replace remaining 1-element arrays") in
v6.1.y.

Can you test it now with 35235e19b393 backported without the above
change?

> But as you say you are not able to reproduce the issue, I guess we
> need to try to get it clearly reproducible first to see we face no
> other fallouts?

I couldn't reproduce it in v6.9-rc4.  Forgot to mention it, sorry.

Yes, further testing would be great to make sure we're not missing
anything else.