linux-kernel - [PATCH v3] perf util: Fix use after free in metric_

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Date:   Fri,  7 Jan 2022 19:21:06 +0100
From:   José Expósito <jose.exposito89@...il.com>
To:     peterz@...radead.org
Cc:     mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, irogers@...gle.com, ak@...ux.intel.com,
        john.garry@...wei.com, linux-perf-users@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        José Expósito <jose.exposito89@...il.com>
Subject: [PATCH v3] perf util: Fix use after free in metric__new

Fix a use after free on the error branch accessing the "metric" struct.

Fixes: b85a4d61d302 (perf metric: Allow modifiers on metrics)
Addresses-Coverity-ID: 1494000
Acked-by: Ian Rogers <irogers@...gle.com>
Reviewed-by: John Garry <john.garry@...wei.com>
Signed-off-by: José Expósito <jose.exposito89@...il.com>

---

v2: Add Fixes and Acked-by tags (thanks to Ian Rogers)
v3: Add Reviewed-by tag (thanks to John Garry)
    Improve patch description
---
 tools/perf/util/metricgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index fffe02aae3ed..4d2fed3aefd1 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -209,8 +209,8 @@ static struct metric *metric__new(const struct pmu_event *pe,
 	m->metric_name = pe->metric_name;
 	m->modifier = modifier ? strdup(modifier) : NULL;
 	if (modifier && !m->modifier) {
-		free(m);
 		expr__ctx_free(m->pctx);
+		free(m);
 		return NULL;
 	}
 	m->metric_expr = pe->metric_expr;
-- 
2.25.1