Oracle will perform instance recovery upon startup. Instance recovery consists of two phases.

First Oracle performs roll-forward phase, where all entries in online redo log are applied to datafiles. After this Oracle performs roll-back phase, where all transactions that have not been commited yet are rolled back. Remember that untill transaction has not been commited or explicitely rolled back it must be still in the rollback segment. Since your transaction has not been commited it will be rolled back during crash recovery.