Fix integer overflow issue; fix
I misunderstood the return value from `snprintf()`, which is NOT number
of characters written in buffer, but the number of character the buffer
has to have to write the complete output.
MODIFY
mrbgems/mruby-sprintf/src/sprintf.c
mrbgems/mruby-sprintf/src/sprintf.c
@@ -1057,17 +1057,21 @@ retry:
need = BIT_DIGITS(i);
}
need += (flags&FPREC) ? prec : 6;
+ if (need < 0) {
+ too_big_width:
+ mrb_raise(mrb, E_ARGUMENT_ERROR,
+ (width > prec ? "width too big" : "prec too big"));
+ }
if ((flags&FWIDTH) && need < width)
need = width;
need += 20;
if (need <= 0) {
- mrb_raise(mrb, E_ARGUMENT_ERROR,
- (width > prec ? "width too big" : "prec too big"));
+ goto too_big_width;
}
CHECK(need);
n = snprintf(&buf[blen], need, fbuf, fval);
- if (n < 0) {
+ if (n < 0 || n >= need) {
mrb_raise(mrb, E_RUNTIME_ERROR, "formatting error");
}
blen += n;

Fix integer overflow issue; fix #4108

I misunderstood the return value from `snprintf()`, which is NOT number
of characters written in buffer, but the number of character the buffer
has to have to write the complete output.