strtoi_lim(const char *str, const char **ep, int llim, int ulim)
{
	int res = 0;
	const char *sp;
	/* we keep track of the number of digits via rulim */
	int rulim;

	for (sp = str, rulim = ulim > 10 ? ulim : 10;
	     res * 10 <= ulim && rulim && *sp >= '0' && *sp <= '9';
	     sp++, rulim /= 10) {
		res *= 10;
		res += *sp - '0';
	}
	if (sp == str) {
		res = -1;
	} else if (res < llim || res > ulim) {
		res = -2;
	}
	*ep = (const char*)sp;
	return res;
}

The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations.