Re: [PATCH] perf test: Fix msan uninitialized use.

[Nick Desaulniers <ndesaulniers@google.com>]

On Wed, Sep 23, 2020 at 2:07 PM 'Ian Rogers' via Clang Built Linux
<clang-built-linux@googlegroups.com> wrote:
>
> Ensure 'st' is initialized before an error branch is taken.
> Fixes test "67: Parse and process metrics" with LLVM msan:
> ==6757==WARNING: MemorySanitizer: use-of-uninitialized-value
>     #0 0x5570edae947d in rblist__exit tools/perf/util/rblist.c:114:2
>     #1 0x5570edb1c6e8 in runtime_stat__exit tools/perf/util/stat-shadow.c:141:2
>     #2 0x5570ed92cfae in __compute_metric tools/perf/tests/parse-metric.c:187:2
>     #3 0x5570ed92cb74 in compute_metric tools/perf/tests/parse-metric.c:196:9
>     #4 0x5570ed92c6d8 in test_recursion_fail tools/perf/tests/parse-metric.c:318:2
>     #5 0x5570ed92b8c8 in test__parse_metric tools/perf/tests/parse-metric.c:356:2
>     #6 0x5570ed8de8c1 in run_test tools/perf/tests/builtin-test.c:410:9
>     #7 0x5570ed8ddadf in test_and_print tools/perf/tests/builtin-test.c:440:9
>     #8 0x5570ed8dca04 in __cmd_test tools/perf/tests/builtin-test.c:661:4
>     #9 0x5570ed8dbc07 in cmd_test tools/perf/tests/builtin-test.c:807:9
>     #10 0x5570ed7326cc in run_builtin tools/perf/perf.c:313:11
>     #11 0x5570ed731639 in handle_internal_command tools/perf/perf.c:365:8
>     #12 0x5570ed7323cd in run_argv tools/perf/perf.c:409:2
>     #13 0x5570ed731076 in main tools/perf/perf.c:539:3
>
> Fixes: commit f5a56570a3f2 ("perf test: Fix memory leaks in parse-metric test")
> Signed-off-by: Ian Rogers <irogers@google.com>

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

Orthogonal:
The case where metricgroup__parse_groups_test() can fail in
__compute_metric() also looks curious. Should &metric_events be passed
to metricgroup__rblist_exit() in that case?

> ---
>  tools/perf/tests/parse-metric.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/tests/parse-metric.c b/tools/perf/tests/parse-metric.c
> index aea4f970fccc..7c1bde01cb50 100644
> --- a/tools/perf/tests/parse-metric.c
> +++ b/tools/perf/tests/parse-metric.c
> @@ -157,6 +157,7 @@ static int __compute_metric(const char *name, struct value *vals,
>         }
>
>         perf_evlist__set_maps(&evlist->core, cpus, NULL);
> +       runtime_stat__init(&st);
>
>         /* Parse the metric into metric_events list. */
>         err = metricgroup__parse_groups_test(evlist, &map, name,
> @@ -170,7 +171,6 @@ static int __compute_metric(const char *name, struct value *vals,
>                 goto out;
>
>         /* Load the runtime stats with given numbers for events. */
> -       runtime_stat__init(&st);
>         load_runtime_stat(&st, evlist, vals);
>
>         /* And execute the metric */
> --
> 2.28.0.681.g6f77f65b4e-goog
>
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-- 
Thanks,
~Nick Desaulniers