The bash multibyte patch has an obvious memory allocation error:

@@ -69,7 +69,7 @@
 +                size_t len = mbstowcs (wcharlist, charlist, 0);
 +                if (len == -1)
 +                  len = 0;
-+                wcharlist = xmalloc (1 + sizeof (wchar_t) * len);
++                wcharlist = xmalloc (sizeof (wchar_t) * (len + 1));
 +                mbstowcs (wcharlist, charlist, 1 + len);
 +              }
 +