[PATCH 5.15 100/244] perf parse-events: Fix segfault when event parser gets an error

[Greg Kroah-Hartman]

From: Adrian Hunter <adrian.hunter@xxxxxxxxx>

commit 2e828582b81f5bc76a4fe8e7812df259ab208302 upstream.

parse_events() is often called with parse_events_error set to NULL.
Make parse_events_error__handle() not segfault in that case.

A subsequent patch changes to avoid passing NULL in the first place.

Fixes: 43eb05d066795bdf ("perf tests: Support 'Track with sched_switch' test for hybrid")
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220809080702.6921-2-adrian.hunter@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 tools/perf/util/parse-events.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -196,9 +196,12 @@ static int tp_event_has_id(const char *d
 void parse_events__handle_error(struct parse_events_error *err, int idx,
 				char *str, char *help)
 {
-	if (WARN(!str, "WARNING: failed to provide error string\n")) {
-		free(help);
-		return;
+	if (WARN(!str, "WARNING: failed to provide error string\n"))
+		goto out_free;
+	if (!err) {
+		/* Assume caller does not want message printed */
+		pr_debug("event syntax error: %s\n", str);
+		goto out_free;
 	}
 	switch (err->num_errors) {
 	case 0:
@@ -224,6 +227,11 @@ void parse_events__handle_error(struct p
 		break;
 	}
 	err->num_errors++;
+	return;
+
+out_free:
+	free(str);
+	free(help);
 }
 
 struct tracepoint_path *tracepoint_id_to_path(u64 config)