They don't do so at the same angle of attack I'd wager. Meaning to fly upside down they have to control pitch in a way that turns the wing to the exact needed angle. Same way they have to control pitch when flying normally to achieve lift.

This pic of real jets doing that side by side confirms what I'm saying (nose is pitched up on the normal-flying plane and 'down' but still up relative to the ground on the inverted one): https://imgur.com/loVcrgO