[PATCH 2/2] perf: do not call list_for_each_entry_safe() on uninitalized list

["Jiri Slaby (SUSE)" <jirislaby@kernel.org>]

In test__pmu_config_helpers(), when evlist__new() fails, the code
jumped to the err_out label, which calls
parse_events_terms__exit(&terms). At that point
parse_events_terms__init(&terms) has not run yet, so the terms list
head is uninitialized and list_for_each_entry_safe() walks a garbage
pointer.

Add a separate err_out_pmu label after the evlist/terms cleanup and
use it for the early evlist allocation failure, so the uninitialized
terms are never touched.

Fixes this compiler warning:
In function ‘parse_events_terms__exit’,
    inlined from ‘test__pmu_config_helpers’ at tests/pmu.c:296:2:
util/parse-events.c:2849:2: warning: ‘terms.terms.next’ may be used uninitialized [-Wmaybe-uninitialized]
tests/pmu.c: In function ‘test__pmu_config_helpers’:
tests/pmu.c:209:28: note: ‘terms’ declared here

Assisted-by: LLM
Fixes: 8e2ef85c66dc ("perf tests: Test evsel__set_config_if_unset() and config change tracking")
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: James Clark <james.clark@linaro.org>
---
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: linux-perf-users@vger.kernel.org
---
 tools/perf/tests/pmu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/pmu.c b/tools/perf/tests/pmu.c
index 13e8d7fa80af..be984e1385df 100644
--- a/tools/perf/tests/pmu.c
+++ b/tools/perf/tests/pmu.c
@@ -223,7 +223,7 @@ static int test__pmu_config_helpers(struct test_suite *test __maybe_unused,
 	evlist = evlist__new();
 	if (evlist == NULL) {
 		pr_err("Failed allocation");
-		goto err_out;
+		goto err_out_pmu;
 	}
 
 	parse_events_terms__init(&terms);
@@ -295,6 +295,7 @@ static int test__pmu_config_helpers(struct test_suite *test __maybe_unused,
 err_out:
 	parse_events_terms__exit(&terms);
 	evlist__put(evlist);
+err_out_pmu:
 	test_pmu_put(dir, pmu);
 	return ret;
 }
-- 
2.56.0