linux-kernel - Re: [PATCH] perf report: fix memory leak in addr2line when called by addr2inlines

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Date:   Wed, 17 May 2017 13:20:49 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Milian Wolff <milian.wolff@...b.com>
Cc:     Linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Yao Jin <yao.jin@...ux.intel.com>, kernel-team@....com
Subject: Re: [PATCH] perf report: fix memory leak in addr2line when called by
 addr2inlines

On Tue, May 16, 2017 at 11:53:59PM +0200, Milian Wolff wrote:
> When a filename was found in addr2line it was duplicated via strdup
> but never freed. Now we pass NULL and handle this gracefully in
> addr2line.
> 
> Detected by Valgrind:
> 
> ==16331== 1,680 bytes in 21 blocks are definitely lost in loss record 148 of 220
> ==16331==    at 0x4C2AF1F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==16331==    by 0x672FA69: strdup (in /usr/lib/libc-2.25.so)
> ==16331==    by 0x52769F: addr2line (srcline.c:256)
> ==16331==    by 0x52769F: addr2inlines (srcline.c:294)
> ==16331==    by 0x52769F: dso__parse_addr_inlines (srcline.c:502)
> ==16331==    by 0x574D7A: inline__fprintf (hist.c:41)
> ==16331==    by 0x574D7A: ipchain__fprintf_graph (hist.c:147)
> ==16331==    by 0x57518A: __callchain__fprintf_graph (hist.c:212)
> ==16331==    by 0x5753CF: callchain__fprintf_graph.constprop.6 (hist.c:337)
> ==16331==    by 0x57738E: hist_entry__fprintf (hist.c:628)
> ==16331==    by 0x57738E: hists__fprintf (hist.c:882)
> ==16331==    by 0x44A20F: perf_evlist__tty_browse_hists (builtin-report.c:399)
> ==16331==    by 0x44A20F: report__browse_hists (builtin-report.c:491)
> ==16331==    by 0x44A20F: __cmd_report (builtin-report.c:624)
> ==16331==    by 0x44A20F: cmd_report (builtin-report.c:1054)
> ==16331==    by 0x4A49CE: run_builtin (perf.c:296)
> ==16331==    by 0x4A4CC0: handle_internal_command (perf.c:348)
> ==16331==    by 0x434371: run_argv (perf.c:392)
> ==16331==    by 0x434371: main (perf.c:530)
> 
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: David Ahern <dsahern@...il.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Yao Jin <yao.jin@...ux.intel.com>
> Signed-off-by: Milian Wolff <milian.wolff@...b.com>
> ---
>  tools/perf/util/srcline.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> index df051a52393c..62cf42c36955 100644
> --- a/tools/perf/util/srcline.c
> +++ b/tools/perf/util/srcline.c
> @@ -253,10 +253,11 @@ static int addr2line(const char *dso_name, u64 addr,
>  	}
>  
>  	if (a2l->found && a2l->filename) {

Not related, but I think it'd be better checking "a2l->found" after
bfd_map_over_sections() and bail out if not.


> -		*file = strdup(a2l->filename);
> -		*line = a2l->line;
> -
> -		if (*file)
> +		if (file)
> +			*file = strdup(a2l->filename);
> +		if (line)
> +			*line = a2l->line;
> +		if (*a2l->filename)

Didn't you want to check a2l->filename being non-NULL instead?  And if
so, this can be :

		if (!file || *file)
>  			ret = 1;
>  	}

Thanks,
Namhyung


>  
> @@ -278,8 +279,6 @@ void dso__free_a2l(struct dso *dso)
>  static struct inline_node *addr2inlines(const char *dso_name, u64 addr,
>  	struct dso *dso)
>  {
> -	char *file = NULL;
> -	unsigned int line = 0;
>  	struct inline_node *node;
>  
>  	node = zalloc(sizeof(*node));
> @@ -291,7 +290,7 @@ static struct inline_node *addr2inlines(const char *dso_name, u64 addr,
>  	INIT_LIST_HEAD(&node->val);
>  	node->addr = addr;
>  
> -	if (!addr2line(dso_name, addr, &file, &line, dso, TRUE, node))
> +	if (!addr2line(dso_name, addr, NULL, NULL, dso, TRUE, node))
>  		goto out_free_inline_node;
>  
>  	if (list_empty(&node->val))
> -- 
> 2.13.0
>