linux-kernel - Re: [PATCH V8 15/25] perf tools: Validate config term maximum value

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Date:	Thu, 6 Aug 2015 16:50:40 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH V8 15/25] perf tools: Validate config term maximum value

Em Fri, Jul 17, 2015 at 07:33:50PM +0300, Adrian Hunter escreveu:
> Currently the value of a PMU config term is silently
> truncated if it is too big. This is an impediment to
> validating the value for other criteria later on i.e.
> the user provides an invalid value that gets truncated
> to a valid one.

Applied
 
> The maximum value validation is only done for the
> parser where the error is passed back to the user. In
> other cases the silent truncation continues so as not
> to affect tools that perhaps rely on it.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/perf/util/pmu.c | 30 +++++++++++++++++++++++++++++-
>  1 file changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index d26ff0ab8410..29797fd9bedc 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -585,6 +585,18 @@ static void pmu_format_value(unsigned long *format, __u64 value, __u64 *v,
>  	}
>  }
>  
> +static __u64 pmu_format_max_value(const unsigned long *format)
> +{
> +	int w;
> +
> +	w = bitmap_weight(format, PERF_PMU_FORMAT_BITS);
> +	if (!w)
> +		return 0;
> +	if (w < 64)
> +		return (1ULL << w) - 1;
> +	return -1;
> +}
> +
>  /*
>   * Term is a string term, and might be a param-term. Try to look up it's value
>   * in the remaining terms.
> @@ -658,7 +670,7 @@ static int pmu_config_term(struct list_head *formats,
>  {
>  	struct perf_pmu_format *format;
>  	__u64 *vp;
> -	__u64 val;
> +	__u64 val, max_val;
>  
>  	/*
>  	 * If this is a parameter we've already used for parameterized-eval,
> @@ -724,6 +736,22 @@ static int pmu_config_term(struct list_head *formats,
>  	} else
>  		return -EINVAL;
>  
> +	max_val = pmu_format_max_value(format->bits);
> +	if (val > max_val) {
> +		if (err) {
> +			err->idx = term->err_val;
> +			if (asprintf(&err->str,
> +				     "value too big for format, maximum is %llu",
> +				     (unsigned long long)max_val) < 0)
> +				err->str = strdup("value too big for format");
> +			return -EINVAL;
> +		}
> +		/*
> +		 * Assume we don't care if !err, in which case the value will be
> +		 * silently truncated.
> +		 */
> +	}
> +
>  	pmu_format_value(format->bits, val, vp, zero);
>  	return 0;
>  }
> -- 
> 1.9.1
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