Jena Malone's role in Batman Vs. Superman is finally made known as the Ultimate Editon has been released online early and the credits have hit the net.
Contrary to speculation, Jena Malone is not playing Barbara Gordon, aka Batgirl, aka Oracle.
In Batman Vs. Superman, Jena Malone plays the DC Comics character Jenet Klyburn where she participates in a lab scene with Amy Adams' Lois Lane.
In the comics, Jenet Klyburn is a doctor and director at Star Labs in Metropolis.
Jena Malone was also featured in Zack Snyder's Sucker Punch, so more or less it seems like Snyder was simply giving a friend a cameo.
The Batman Vs. Superman Ultimate Edition can be purchased through Amazon.