linux-kernel - Re: [PATCH] perf parse-events: fix 3 use after frees

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Message-ID: <20200314135925.GA492969@krava>
Date:   Sat, 14 Mar 2020 14:59:25 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Leo Yan <leo.yan@...aro.org>, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH] perf parse-events: fix 3 use after frees

On Fri, Mar 13, 2020 at 04:02:49PM -0700, Ian Rogers wrote:
> Reproducible with a clang asan build and then running perf test in
> particular 'Parse event definition strings'.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/util/parse-events.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index a14995835d85..593b6b03785d 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -1449,7 +1449,7 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
>  		evsel = __add_event(list, &parse_state->idx, &attr, NULL, pmu, NULL,
>  				    auto_merge_stats, NULL);
>  		if (evsel) {
> -			evsel->pmu_name = name;
> +			evsel->pmu_name = name ? strdup(name) : NULL;
>  			evsel->use_uncore_alias = use_uncore_alias;
>  			return 0;
>  		} else {
> @@ -1497,7 +1497,7 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
>  		evsel->snapshot = info.snapshot;
>  		evsel->metric_expr = info.metric_expr;
>  		evsel->metric_name = info.metric_name;
> -		evsel->pmu_name = name;
> +		evsel->pmu_name = name ? strdup(name) : NULL;

so it's pmu->name pointer.. does pmu get destroyed before the evsel?
also should we free that then like below?

>  		evsel->use_uncore_alias = use_uncore_alias;
>  		evsel->percore = config_term_percore(&evsel->config_terms);
>  	}
> @@ -1547,7 +1547,7 @@ int parse_events_multi_pmu_add(struct parse_events_state *parse_state,
>  				if (!parse_events_add_pmu(parse_state, list,
>  							  pmu->name, head,
>  							  true, true)) {
> -					pr_debug("%s -> %s/%s/\n", config,
> +					pr_debug("%s -> %s/%s/\n", str,

nice catch ;-)

>  						 pmu->name, alias->str);
>  					ok++;
>  				}
> -- 
> 2.25.1.481.gfbce0eb801-goog
> 

thanks,
jirka


---
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 816d930d774e..15ccd193483f 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1287,6 +1287,7 @@ void perf_evsel__exit(struct evsel *evsel)
 	perf_thread_map__put(evsel->core.threads);
 	zfree(&evsel->group_name);
 	zfree(&evsel->name);
+	zfree(&evsel->pmu_name);
 	perf_evsel__object.fini(evsel);
 }