linux-kernel - [PATCH -tip ] [BUGFIX] perf/probe: Fix to handle errors in line

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Message-ID: <20140402054831.19080.27006.stgit@ltc230.yrl.intra.hitachi.co.jp>
Date:	Wed, 02 Apr 2014 14:48:31 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>, Ingo Molnar <mingo@...nel.org>
Subject: [PATCH -tip ] [BUGFIX] perf/probe: Fix to handle errors in
 line_range searching

As Namhyung reported(https://lkml.org/lkml/2014/4/1/89),
current perf-probe -L option doesn't handle errors in line-range
searching correctly. It causes a SEGV if an error occured in the
line-range searching.

  ----
  $ perf probe -x ./perf -v -L map__load
  Open Debuginfo file: /home/namhyung/project/linux/tools/perf/perf
  fname: util/map.c, lineno:153
  New line range: 153 to 2147483647
  path: (null)
  Segmentation fault (core dumped)
  ----

This is because line_range_inline_cb() ignores errors
from find_line_range_by_line() which means that lr->path is
already freed on the error path in find_line_range_by_line().
As a result, get_real_path() accesses the lr->path and it
causes a NULL pointer exception.

This fixes line_range_inline_cb() to handle the error correctly,
and report it to the caller.

Anyway, this just fixes a possible SEGV bug, Namhyung's patch
is also required.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Reported-by: Namhyung Kim <namhyung@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Namhyung Kim <namhyung.kim@....com>
Cc: Jiri Olsa <jolsa@...hat.com>
---
 tools/perf/util/probe-finder.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index df02386..edcd2ff 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1473,14 +1473,15 @@ static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
 
 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
 {
-	find_line_range_by_line(in_die, data);
+	int ret = find_line_range_by_line(in_die, data);
 
 	/*
 	 * We have to check all instances of inlined function, because
 	 * some execution paths can be optimized out depends on the
-	 * function argument of instances
+	 * function argument of instances. However, if an error occurs,
+	 * it should be handled by the caller.
 	 */
-	return 0;
+	return ret < 0 ? ret : 0;
 }
 
 /* Search function definition from function name */


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