Johnson and Smith are the Cowboys’ only players to spend time on the COVID-19 list thus far, though fullback Jamize Olawale, cornerback Maurice Canady and rookie receiver Stephen Guidry opted out of the 2020 season.
Johnson was on his way to finding a spot with the team a year ago before injuring his arm. He spent his rookie season on injured reserve.
His return led the team to waive undrafted rookie receiver Kendrick Rogers.
Smith, a first-year player from Alabama, spent training camp with the Jaguars in 2019. Jacksonville cut him out of the preseason.
Smith was not with a team last season but had a brief stint with the XFL before signing with the Cowboys in April.