Is the Farewell Tawaf valid if one is in doubt about being ritually pure from major defilement (janabah) while performing it?

Circumambulating (Tawaf) without ablution (Wudu') is a matter of disagreement, and the majority of jurists hold that it is invalid. As for doubting the state of janabah (major ritual impurity), it has no effect, because the default state is purity unless one is certain of the emission of semen, and certainty is not nullified by doubt. Based on this, the Tawaf is valid and there is no blame.