Add negative check in `mrb_str_resize`; fix
MODIFY
src/string.c
src/string.c
@@ -708,6 +708,9 @@ mrb_str_resize(mrb_state *mrb, mrb_value str, mrb_int len)
mrb_int slen;
struct RString *s = mrb_str_ptr(str);
+ if (len < 0) {
+ mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative (or overflowed) string size");
+ }
mrb_str_modify(mrb, s);
slen = RSTR_LEN(s);
if (len != slen) {

Add negative check in `mrb_str_resize`; fix #4062