plumb a leak with pos().

#! perl
while (1) {
	my $a = "\x{1ff}"; $a =~ /\x{1ff}/g; pos($a);
}
__END__

p4raw-id: //depot/perl@21866

1 files changed, 2 insertions, 1 deletions

diff --git a/sv.c b/sv.c
index dc089b8386..6f53c587e4 100644
--- a/sv.c
+++ b/sv.c
@@ -6056,7 +6056,8 @@ Perl_sv_pos_b2u(pTHX_ register SV* sv, I32* offsetp)
 	    assert(mg);
 
 	    if (!mg->mg_ptr) {
-		Newz(0, cache, PERL_MAGIC_UTF8_CACHESIZE * 2, STRLEN);
+		mg->mg_len = PERL_MAGIC_UTF8_CACHESIZE * 2;
+		Newz(0, cache, mg->mg_len, STRLEN);
 		mg->mg_ptr = (char *) cache;
 	    }
 	    assert(cache);