Read of uninitialized heap found by Third Degree

(e.g. in t/op/subst.t)

p4raw-id: //depot/perl@16601

1 files changed, 3 insertions, 1 deletions

diff --git a/scope.c b/scope.c
index a1fdfd120e..4ff903fe3e 100644
--- a/scope.c
+++ b/scope.c
@@ -80,7 +80,9 @@ Perl_new_stackinfo(pTHX_ I32 stitems, I32 cxitems)
     si->si_cxmax = cxitems - 1;
     si->si_cxix = -1;
     si->si_type = PERLSI_UNDEF;
-    New(56, si->si_cxstack, cxitems, PERL_CONTEXT);
+    /* Needs to be Newz() because PUSHSUBST() in pp_subst()
+     * might otherwise read uninitialized heap. */
+    Newz(56, si->si_cxstack, cxitems, PERL_CONTEXT);
     return si;
 }