linux-kernel - Re: [PATCH v1] fs:smb:Fix unsigned expression compared with zero

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Message-ID: <88381d01-f269-cf1b-00c0-ca5204f2a65e@talpey.com>
Date:   Sat, 1 Jul 2023 10:43:15 -0400
From:   Tom Talpey <tom@...pey.com>
To:     Wang Ming <machel@...o.com>, Namjae Jeon <linkinjeon@...nel.org>,
        Steve French <sfrench@...ba.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     opensource.kernel@...o.com
Subject: Re: [PATCH v1] fs:smb:Fix unsigned expression compared with zero

On 7/1/2023 1:55 AM, Wang Ming wrote:
> The return value of the ksmbd_vfs_getcasexattr() is long.
> However, the return value is being assigned to an unsignef
> long variable 'v_len',so making 'v_len' to long. Also, when
> comparing to zero in the following code, no type conversion
> is required.

I agree with the fix, but this commit message is confusing.
The type is strictly speaking not "long", it's ssize_t. And
the final sentence seems unnecessary.

"The return value of the ksmbd_vfs_getcasexattr() is signed.
  However, the return value is being assigned to an unsigned
  variable and subsequently recasted, causing warnings. Use
  a signed type."

or similar.

With this clarified...
Acked-by: Tom Talpey <tom@...pey.com>


> 
> silence the warning:
> ./fs/smb/server/vfs.c:WARNING: Unsigned expression compared
> with zero: v_len > 0
> 
> Signed-off-by: Wang Ming <machel@...o.com>
> ---
>   fs/smb/server/vfs.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
> index e35914457..e605ee96b 100644
> --- a/fs/smb/server/vfs.c
> +++ b/fs/smb/server/vfs.c
> @@ -412,7 +412,8 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
>   {
>          char *stream_buf = NULL, *wbuf;
>          struct mnt_idmap *idmap = file_mnt_idmap(fp->filp);
> -       size_t size, v_len;
> +       size_t size;
> +       ssize_t v_len;
>          int err = 0;
> 
>          ksmbd_debug(VFS, "write stream data pos : %llu, count : %zd\n",
> @@ -429,9 +430,9 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
>                                         fp->stream.name,
>                                         fp->stream.size,
>                                         &stream_buf);
> -       if ((int)v_len < 0) {
> +       if (v_len < 0) {
>                  pr_err("not found stream in xattr : %zd\n", v_len);
> -               err = (int)v_len;
> +               err = v_len;
>                  goto out;
>          }
> 
> --
> 2.25.1
> 
> 
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