linux-kernel - [PATCH 01/20] perf nsinfo: fix refcounting

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Message-Id: <55223bc8821b34ccb01f92ef1401c02b6a32e61f.1626343282.git.rickyman7@gmail.com>
Date:   Thu, 15 Jul 2021 18:07:06 +0200
From:   Riccardo Mancini <rickyman7@...il.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ian Rogers <irogers@...gle.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org,
        Riccardo Mancini <rickyman7@...il.com>
Subject: [PATCH 01/20] perf nsinfo: fix refcounting

ASan reports a memory leak of nsinfo during the execution of the perf
test "31: Lookup mmap thread".
The leak is caused by a refcounted variable being replaced without
dropping the refcount.

This patch makes sure that the refcnt of nsinfo is decreased whenever
a refcounted variable is replaced with a new value.

Signed-off-by: Riccardo Mancini <rickyman7@...il.com>
---
 tools/perf/builtin-inject.c   | 5 +++--
 tools/perf/util/map.c         | 2 ++
 tools/perf/util/probe-event.c | 4 +++-
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 5d6f583e2cd35be0..ffd2b25039e36e1d 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -361,9 +361,10 @@ static struct dso *findnew_dso(int pid, int tid, const char *filename,
 		dso = machine__findnew_dso_id(machine, filename, id);
 	}
 
-	if (dso)
+	if (dso) {
+		nsinfo__put(dso->nsinfo);
 		dso->nsinfo = nsi;
-	else
+	} else
 		nsinfo__put(nsi);
 
 	thread__put(thread);
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 8af693d9678cefe0..72e7f3616157ead4 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -192,6 +192,8 @@ struct map *map__new(struct machine *machine, u64 start, u64 len,
 			if (!(prot & PROT_EXEC))
 				dso__set_loaded(dso);
 		}
+
+		nsinfo__put(dso->nsinfo);
 		dso->nsinfo = nsi;
 
 		if (build_id__is_defined(bid))
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index c14e1d228e56b1c6..e05750cea34c3a95 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -179,8 +179,10 @@ struct map *get_target_map(const char *target, struct nsinfo *nsi, bool user)
 		struct map *map;
 
 		map = dso__new_map(target);
-		if (map && map->dso)
+		if (map && map->dso) {
+			nsinfo__put(map->dso->nsinfo);
 			map->dso->nsinfo = nsinfo__get(nsi);
+		}
 		return map;
 	} else {
 		return kernel_get_module_map(target);
-- 
2.31.1