linux-kernel - [PATCH 5.4 021/108] perf probe: Fix dso->nsinfo refcounting

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Message-Id: <20210726153832.374187674@linuxfoundation.org>
Date:   Mon, 26 Jul 2021 17:38:22 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Riccardo Mancini <rickyman7@...il.com>,
        Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...hat.com>,
        Krister Johansen <kjlx@...pleofstupid.com>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 021/108] perf probe: Fix dso->nsinfo refcounting

From: Riccardo Mancini <rickyman7@...il.com>

[ Upstream commit dedeb4be203b382ba7245d13079bc3b0f6d40c65 ]

ASan reports a memory leak of nsinfo during the execution of:

 # 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>
Fixes: 544abd44c7064c8a ("perf probe: Allow placing uprobes in alternate namespaces.")
Cc: Ian Rogers <irogers@...gle.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Krister Johansen <kjlx@...pleofstupid.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lore.kernel.org/lkml/55223bc8821b34ccb01f92ef1401c02b6a32e61f.1626343282.git.rickyman7@gmail.com
[ Split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/perf/util/probe-event.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index a5cb1a3a1064..6357ac508ad1 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -175,8 +175,10 @@ 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);
-- 
2.30.2