linux-kernel - Re: [PATCH] smb: client: fix refcount leak in smb2_set_path

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Message-ID: <CAH2r5mu7s4p88RhUbCm5mqUvEVM60OOTTJOZ+rz09nFfc+t3mQ@mail.gmail.com>
Date: Tue, 4 Nov 2025 10:12:13 -0600
From: Steve French <smfrench@...il.com>
To: Shuhao Fu <sfual@....ust.hk>
Cc: Steve French <sfrench@...ba.org>, Paulo Alcantara <pc@...guebit.org>, 
	Ronnie Sahlberg <ronniesahlberg@...il.com>, Shyam Prasad N <sprasad@...rosoft.com>, 
	Tom Talpey <tom@...pey.com>, Bharath SM <bharathsm@...rosoft.com>, linux-cifs@...r.kernel.org, 
	samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] smb: client: fix refcount leak in smb2_set_path_attr

There are multiple callers - are there callers that don't call
"set_writeable_path()" ?    And so could cause the reverse refcount
issue?

On Tue, Nov 4, 2025 at 9:21 AM Shuhao Fu <sfual@....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@....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)
>
>


-- 
Thanks,

Steve