linux-kernel - Re: [PATCH v3] memory leak fix while calling system

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Message-ID: <87haqx8fy1.fsf@sejong.aot.lge.com>
Date:	Mon, 17 Sep 2012 12:51:34 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	liang xie <xieliang007@...il.com>
Cc:	linux-perf-users@...r.kernel.org, acme@...stprotocols.net,
	balbi@...com, a.p.zijlstra@...llo.nl, mingo@...e.hu,
	paulus@...ba.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] memory leak fix while calling system_path

Hi,

On Fri, 14 Sep 2012 11:14:13 +0800, liang xie wrote:
> memory leak fix while calling system_path
>
> Since v1: Remove an unnecessary null pointer check per Felipe's comments
> Since v2: Make system_path&perf_exec_path always return dynamically
> allocated string
>
> Signed-off-by: xieliang <xieliang@...omi.com>
> ---
>  tools/perf/builtin-help.c   |   12 +++++++++---
>  tools/perf/builtin-script.c |   13 ++++++++++---
>  tools/perf/perf.c           |    8 ++++++--
>  tools/perf/util/config.c    |   16 +++++-----------
>  tools/perf/util/exec_cmd.c  |   26 +++++++++++++++-----------
>  tools/perf/util/exec_cmd.h  |    4 ++--
>  tools/perf/util/help.c      |    6 ++++--
>  7 files changed, 51 insertions(+), 34 deletions(-)
>
> diff --git a/tools/perf/builtin-help.c b/tools/perf/builtin-help.c
> index 6d5a8a7..180a5bd 100644
> --- a/tools/perf/builtin-help.c
> +++ b/tools/perf/builtin-help.c
> @@ -321,12 +321,13 @@ static void setup_man_path(void)
>  {
>  	struct strbuf new_path = STRBUF_INIT;
>  	const char *old_path = getenv("MANPATH");
> +	char *man_path = system_path(PERF_MAN_PATH);

I think the return value of system_path and perf_exec_path should be
checked since they can return NULL as strdup() does.


[snip]
> diff --git a/tools/perf/util/exec_cmd.c b/tools/perf/util/exec_cmd.c
> index 7adf4ad..1ace941 100644
> --- a/tools/perf/util/exec_cmd.c
> +++ b/tools/perf/util/exec_cmd.c
> @@ -9,17 +9,19 @@
>  static const char *argv_exec_path;
>  static const char *argv0_path;
>
> -const char *system_path(const char *path)
> +char *system_path(const char *path)
>  {
> -	static const char *prefix = PREFIX;
> -	struct strbuf d = STRBUF_INIT;
> +	char *new_path = NULL;
>
>  	if (is_absolute_path(path))
> -		return path;
> +		return strdup(path);
>
> -	strbuf_addf(&d, "%s/%s", prefix, path);
> -	path = strbuf_detach(&d, NULL);
> -	return path;
> +	new_path = malloc((strlen(PREFIX) + strlen(path) + 2));
> +	if (!new_path)
> +		die("malloc");
> +
> +	sprintf(new_path, "%s/%s", PREFIX, path);
> +	return new_path;

AFAIK strbuf allocates memory internally, so why this code is needed?

Thanks,
Namhyung
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