perf header: Fix bogus group name

When processing event group descriptor in perf file header, we reuse an
allocated group name but forgot to prevent it from freeing.

Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1384741244-7271-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/header.c

@@ -2078,8 +2078,10 @@ static int process_group_desc(struct perf_file_section *section __maybe_unused,
 		if (evsel->idx == (int) desc[i].leader_idx) {
 			evsel->leader = evsel;
 			/* {anon_group} is a dummy name */
-			if (strcmp(desc[i].name, "{anon_group}"))
+			if (strcmp(desc[i].name, "{anon_group}")) {
 				evsel->group_name = desc[i].name;
+				desc[i].name = NULL;
+			}
 			evsel->nr_members = desc[i].nr_members;
 
 			if (i >= nr_groups || nr > 0) {