Not that I am aware of. However the Pope knows he has crossed a very thin line. He may choose to retire or set up a most unholy war within the church.
That "validly elected" part may be debatable though. There were some things about Pope Benedict's resignation which were rather sketchy, to say the least. It really didn't pass the smell test.
If it could be shown that Pope Benedict's abdication was not fully voluntary --- if there were force, manipulation or fraud involved --- his abdication would be invalid, and therefore the conclave that elected Pope Francis would be invalid, and Francis would be, technically, an anti-pope.
I can imagine this issue coming to a crisis if Benedict dies. At that point, some Cardinal could say "We need to have a conclave to elect a new pope," and when somebody objects, "But we have a pope, Francis", the skulduggery that was behind his election (the Sant-Gallen Group, or "Mafia" as Cardinnal Daneels called it) would start to come out into the open.
It would be a real mess. It's hard to envision a good outcome.
But I believe in the Holy Spirit.