SMB3: avoid confusing warning message on mount to Azure

commit ebcd6de upstream.

Mounts to Azure cause an unneeded warning message in dmesg
   "CIFS: VFS: parse_server_interfaces: incomplete interface info"

Azure rounds up the size (by 8 additional bytes, to a
16 byte boundary) of the structure returned on the query
of the server interfaces at mount time.  This is permissible
even though different than other servers so do not log a warning
if query network interfaces response is only rounded up by 8
bytes or fewer.

CC: Stable <stable@vger.kernel.org>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/cifs/smb2ops.c

@@ -478,7 +478,8 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 		goto out;
 	}
 
-	if (bytes_left || p->Next)
+	/* Azure rounds the buffer size up 8, to a 16 byte boundary */
+	if ((bytes_left > 8) || p->Next)
 		cifs_dbg(VFS, "%s: incomplete interface info\n", __func__);