linux-kernel - Re: [PATCH 5/5] perf tool: Add basic event modifier sanity check

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Date:	Tue, 13 Nov 2012 11:22:24 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 5/5] perf tool: Add basic event modifier sanity check

Hi Jiri,

On Mon, 12 Nov 2012 18:34:04 +0100, Jiri Olsa wrote:
> Updating event parser to allow any non zero string containing
> [ukhpGH] characters for event modifier.
>
> The modifier sanity is checked later in parse-event object logic.
> The check validates modifier to contain only one instance of any
> modifier (apart from 'p') present.
[snip]
> +/*
> + * Basic modifier sanity check to validate it contains only one
> + * instance of any modifier (apart from 'p') present.
> + */
> +static int check_modifier(char *str)
> +{
> +	char *p = str;
> +
> +	while (*p) {
> +		if (*p != 'p' && strchr(p + 1, *p))
> +			return -1;
> +		p++;
> +	}

How about adding a length check too?  i.e. something like:

	if ((p - str) > strlen("ukhGHppp"))
        	return -1;

Thanks,
Namhyung

> +
> +	return 0;
> +}
> +
>  int parse_events__modifier_event(struct list_head *list, char *str, bool add)
>  {
>  	struct perf_evsel *evsel;
> @@ -730,6 +747,9 @@ int parse_events__modifier_event(struct list_head *list, char *str, bool add)
>  	if (str == NULL)
>  		return 0;
>  
> +	if (check_modifier(str))
> +		return -EINVAL;
> +
>  	if (!add && get_event_modifier(&mod, str, NULL))
>  		return -EINVAL;
>  
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 66959fa..e9d1134 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -82,7 +82,7 @@ num_hex		0x[a-fA-F0-9]+
>  num_raw_hex	[a-fA-F0-9]+
>  name		[a-zA-Z_*?][a-zA-Z0-9_*?]*
>  name_minus	[a-zA-Z_*?][a-zA-Z0-9\-_*?]*
> -modifier_event	[ukhpGH]{1,8}
> +modifier_event	[ukhpGH]+
>  modifier_bp	[rwx]{1,3}
>  
>  %%
--
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