perf parse-events: Fix segfault when event parser gets an error

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@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20220809080702.6921-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 206c766..dfc7d7a 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -2256,9 +2256,12 @@ void parse_events_error__exit(struct parse_events_error *err)
 void parse_events_error__handle(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:
@@ -2284,6 +2287,11 @@ void parse_events_error__handle(struct parse_events_error *err, int idx,
                break;
        }
        err->num_errors++;
+       return;
+
+out_free:
+       free(str);
+       free(help);
 }
 
 #define MAX_WIDTH 1000