[PATCH] smb: client: fix refcount leak in smb2_set_path_attr

[Henrique Carvalho]

On 11/4/25 1:12 PM, Steve French via samba-technical wrote:
> There are multiple callers - are there callers that don't call
> "set_writeable_path()" ?    And so could cause the reverse refcount
> issue?

Yes... Even if it does not cause an issue today, that fix looks like it
belongs inside smb2_rename_path?

> 
> On Tue, Nov 4, 2025 at 9:21 AM Shuhao Fu <sfual at cse.ust.hk> wrote:
>>
>> Fix refcount leak in `smb2_set_path_attr` when path conversion fails.
>>
>> Function `cifs_get_writable_path` returns `cfile` with its reference
>> counter `cfile->count` increased on success. Function `smb2_compound_op`
>> would decrease the reference counter for `cfile`, as stated in its
>> comment. By calling `smb2_rename_path`, the reference counter of `cfile`
>> would leak if `cifs_convert_path_to_utf16` fails in `smb2_set_path_attr`.
>>
>> Fixes: 8de9e86c67ba ("cifs: create a helper to find a writeable handle by path name")
>> Signed-off-by: Shuhao Fu <sfual at cse.ust.hk>
>> ---
>>  fs/smb/client/smb2inode.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c
>> index 09e3fc81d..69cb81fa0 100644
>> --- a/fs/smb/client/smb2inode.c
>> +++ b/fs/smb/client/smb2inode.c
>> @@ -1294,6 +1294,8 @@ static int smb2_set_path_attr(const unsigned int xid, struct cifs_tcon *tcon,
>>         smb2_to_name = cifs_convert_path_to_utf16(to_name, cifs_sb);
>>         if (smb2_to_name == NULL) {
>>                 rc = -ENOMEM;
>> +               if (cfile)
>> +                       cifsFileInfo_put(cfile);
>>                 goto smb2_rename_path;
>>         }
>>         in_iov.iov_base = smb2_to_name;
>> --
>> 2.39.5 (Apple Git-154)
>>
>>
> 
> 

-- 
Henrique
SUSE Labs