linux-kernel - Re: [RFC PATCH] perf util: asprintf helper for leak sanitizer

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Date:   Tue, 13 Jun 2023 16:50:32 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] perf util: asprintf helper for leak sanitizer

Em Tue, Jun 13, 2023 at 12:16:38PM -0700, Ian Rogers escreveu:
> asprintf is a source of memory leaks but produces bad stack traces on
> my Debian linux. This patch adds a simple asprintf implementation to
> util.c that works around it.

So is this something to report to the glibc maintainers or debian?

- Arnaldo
 
> Before output:
> ```
> ==1541752==ERROR: LeakSanitizer: detected memory leaks
> 
> Direct leak of 10 byte(s) in 1 object(s) allocated from:
>     #0 0x7f90c76b89cf in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:69
>     #1 0x7f90c649d2c7 in __vasprintf_internal libio/vasprintf.c:71
>     #2 0x55ad9b79afbf  (/tmp/perf/perf+0x850fbf)
> 
> SUMMARY: AddressSanitizer: 10 byte(s) leaked in 1 allocation(s).
> ```
> 
> After output:
> ```
> ==1545918==ERROR: LeakSanitizer: detected memory leaks
> 
> Direct leak of 10 byte(s) in 1 object(s) allocated from:
>     #0 0x7f2755a7077b in __interceptor_strdup ../../../../src/libsanitizer/asan/asan_interceptors.cpp:439
>     #1 0x564986a8df31 in asprintf util/util.c:566
>     #2 0x5649869b5901 in metricgroup__lookup_default_metricgroup util/metricgroup.c:1520
>     #3 0x5649869b5e57 in metricgroup__lookup_create util/metricgroup.c:1579
>     #4 0x5649869b6ddc in parse_groups util/metricgroup.c:1698
>     #5 0x5649869b7714 in metricgroup__parse_groups util/metricgroup.c:1771
>     #6 0x5649867da9d5 in add_default_attributes tools/perf/builtin-stat.c:2164
>     #7 0x5649867ddbfb in cmd_stat tools/perf/builtin-stat.c:2707
>     #8 0x5649868fa5a2 in run_builtin tools/perf/perf.c:323
>     #9 0x5649868fab13 in handle_internal_command tools/perf/perf.c:377
>     #10 0x5649868faedb in run_argv tools/perf/perf.c:421
>     #11 0x5649868fb443 in main tools/perf/perf.c:537
>     #12 0x7f2754846189 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
> 
> SUMMARY: AddressSanitizer: 10 byte(s) leaked in 1 allocation(s).
> ```
> 
> RFC: is this useful for others? Should we have a build flag for it?
> ---
>  tools/perf/util/util.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
> index c1fd9ba6d697..57eb528c5fed 100644
> --- a/tools/perf/util/util.c
> +++ b/tools/perf/util/util.c
> @@ -552,3 +552,22 @@ int sched_getcpu(void)
>  	return -1;
>  }
>  #endif
> +
> +int asprintf(char **restrict strp, const char *restrict fmt, ...)
> +{
> +	char buf[1024];
> +	va_list ap;
> +	int size;
> +	char *result;
> +
> +	va_start(ap, fmt);
> +	size = vsnprintf(buf, sizeof(buf), fmt, ap);
> +	if (size < (int)sizeof(buf))
> +		result = strdup(buf);
> +	else
> +		size = vasprintf(&result, fmt, ap);
> +
> +	*strp = result;
> +	va_end(ap);
> +	return size;
> +}
> -- 
> 2.41.0.162.gfafddb0af9-goog
> 

-- 

- Arnaldo