overrun screw n.

[C programming] A variety of fandango on core produced by scribbling past the end of an array (C implementations typically have no checks for this error). This is relatively benign and easy to spot if the array is static; if it is auto, the result may be to smash the stack -- often resulting in heisenbugs of the most diabolical subtlety. The term `overrun screw' is used esp. of scribbles beyond the end of arrays allocated with malloc(3); this typically trashes the allocation header for the next block in the arena, producing massive lossage within malloc and often a core dump on the next operation to use stdio(3) or malloc(3) itself. See spam, overrun; see also memory leak, memory smash, aliasing bug, precedence lossage, fandango on core, secondary damage.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.