[LTP] [PATCH 06/15] ujson: reader: Check for signed integer overflow

[Cyril Hrubis]

Hi!
>  static int get_int(ujson_reader *buf, struct ujson_val *res)
>  {
> -	long val = 0;
> +	unsigned long val = 0;
>  	int sign = 1;
>  
>  	if (eatb(buf, '-')) {
> @@ -325,17 +326,25 @@ static int get_int(ujson_reader *buf, struct ujson_val *res)
>  		return 1;
>  	}
>  
> +	unsigned long max = (sign < 0) ? (unsigned long)LONG_MAX + 1UL : (unsigned long)LONG_MAX;
> +
>  	while (is_digit(peekb(buf))) {
> -		val *= 10;
> -		val += getb(buf) - '0';
> -		//TODO: overflow?
> +		unsigned int d = getb(buf) - '0';
> +
> +		if (val > (max - d) / 10) {
> +			ujson_err(buf, "Integer overflow");
> +			return 1;
> +		}
> +
> +		val = val * 10 + d;
>  	}
>  
>  	if (sign < 0)
> -		val = -val;
> +		res->val_int = (long)(0UL - val);

This would be better res->val_int = -(long)val;


And I do not like the code that much, but I think that we cannot do much
better without having separate functions for possitive and negative
numbers.

-- 
Cyril Hrubis
chrubis@suse.cz