FIXED: undo/1: calling hooks while backtracking could corrupt choicep…

…oint. Reported by Fernando Saenz Perez.
SWI-Prolog · Oct 23, 2023 · 7f0b8ab · 7f0b8ab
1 parent b4e4a19
commit 7f0b8ab
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/src/pl-vmi.c b/src/pl-vmi.c
@@ -6858,9 +6858,14 @@ VMH(deep_backtrack, 0, (), ())
     if ( UNDO_SCHEDULED(LD) )
     { int rc;
 
+      lTop = (LocalFrame)(ch+1);
+      FR->clause = NULL;
+      if ( LD->mark_bar != NO_MARK_BAR )
+	LD->mark_bar = gTop;
       SAVE_REGISTERS(QID);
       rc = run_undo_hooks();
       LOAD_REGISTERS(QID);
+      ch = BFR;			/* can be shifted */
       if ( !rc )
 	THROW_EXCEPTION;
     }