8351081: Off-by-one error in ShenandoahCardCluster

Cesar Soares Lucas · William Kemper · commit 38b4d46c1ff3 · 2025-03-04T21:44:40.000Z
Reviewed-by: wkemper
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahScanRemembered.hpp b/src/hotspot/share/gc/shenandoah/shenandoahScanRemembered.hpp
@@ -402,7 +402,7 @@ class ShenandoahCardCluster: public CHeapObj<mtGC> {
 
   ShenandoahCardCluster(ShenandoahDirectCardMarkRememberedSet* rs) {
     _rs = rs;
-    _object_starts = NEW_C_HEAP_ARRAY(crossing_info, rs->total_cards(), mtGC);
+    _object_starts = NEW_C_HEAP_ARRAY(crossing_info, rs->total_cards() + 1, mtGC); // the +1 is to account for card table guarding entry
     for (size_t i = 0; i < rs->total_cards(); i++) {
       _object_starts[i].short_word = 0;
     }

Original file line number	Diff line number	Diff line change
`@@ -402,7 +402,7 @@ class ShenandoahCardCluster: public CHeapObj<mtGC> {`
`402`	`402`
`403`	`403`	`ShenandoahCardCluster(ShenandoahDirectCardMarkRememberedSet* rs) {`
`404`	`404`	`_rs = rs;`
`405`		`- _object_starts = NEW_C_HEAP_ARRAY(crossing_info, rs->total_cards(), mtGC);`
	`405`	`+ _object_starts = NEW_C_HEAP_ARRAY(crossing_info, rs->total_cards() + 1, mtGC); // the +1 is to account for card table guarding entry`
`406`	`406`	`for (size_t i = 0; i < rs->total_cards(); i++) {`
`407`	`407`	`_object_starts[i].short_word = 0;`
`408`	`408`	`}`