linux-kernel - [PATCH] perf script: fix invalid read

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Date:   Thu,  2 Apr 2020 14:43:38 +0200
From:   Andreas Gerstmayr <agerstmayr@...hat.com>
To:     linux-perf-users@...r.kernel.org
Cc:     Andreas Gerstmayr <agerstmayr@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] perf script: fix invalid read

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@...hat.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