[PATCH] perf script: fix invalid read

From: Andreas Gerstmayr <agerstmayr@redhat.com>
To: linux-perf-users@vger.kernel.org
Cc: Andreas Gerstmayr <agerstmayr@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] perf script: fix invalid read
Date: Thu,  2 Apr 2020 14:43:38 +0200	[thread overview]
Message-ID: <20200402124337.419456-1-agerstmayr@redhat.com> (raw)
In-Reply-To: <05e0d633-54b4-fb3b-3d08-8963271017ea@amd.com>

closedir(lang_dir) frees the memory of script_dirent->d_name, which
gets accessed in the next line in a call to scnprintf().

Valgrind report:

Invalid read of size 1
==413557==    at 0x483CBE6: strlen (vg_replace_strmem.c:461)
==413557==    by 0x4DD45FD: __vfprintf_internal (vfprintf-internal.c:1688)
==413557==    by 0x4DE6679: __vsnprintf_internal (vsnprintf.c:114)
==413557==    by 0x53A037: vsnprintf (stdio2.h:80)
==413557==    by 0x53A037: scnprintf (vsprintf.c:21)
==413557==    by 0x435202: get_script_path (builtin-script.c:3223)
==413557==  Address 0x52e7313 is 1,139 bytes inside a block of size 32,816 free'd
==413557==    at 0x483AA0C: free (vg_replace_malloc.c:540)
==413557==    by 0x4E303C0: closedir (closedir.c:50)
==413557==    by 0x4351DC: get_script_path (builtin-script.c:3222)

Signed-off-by: Andreas Gerstmayr <agerstmayr@redhat.com>
---
 tools/perf/builtin-script.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 656b347f6dd8..170af13b4d53 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -3218,10 +3218,10 @@ static char *get_script_path(const char *script_root, const char *suffix)
 			__script_root = get_script_root(script_dirent, suffix);
 			if (__script_root && !strcmp(script_root, __script_root)) {
 				free(__script_root);
-				closedir(lang_dir);
 				closedir(scripts_dir);
 				scnprintf(script_path, MAXPATHLEN, "%s/%s",
 					  lang_path, script_dirent->d_name);
+				closedir(lang_dir);
 				return strdup(script_path);
 			}
 			free(__script_root);
-- 
2.25.1

