Live path control flow integrity

Per-Input Control Flow Integrity (PICFI) represents a recent advance in dynamic CFI techniques. PICFI starts with the empty CFG of a program and lazily adds edges to the CFG during execution according to concrete inputs. However, this CFG grows monotonically, i.e., invalid edges are never removed when corresponding control flow transfers (via indirect calls) become illegal (i.e., will never be executed again). This paper presents LPCFI, Live Path Control Flow Integrity, to more precisely enforce forward edge CFI using a dynamically computed CFG by both adding and removing edges for all indirect control flow transfers from function pointer calls, thereby raising the bar against control flow hijacking attacks.