releases/5.13.6/perf-probe-fix-dso-nsinfo-refcounting.patch

From 24e4b406552ebc851df64c8d27c0ea3124293b65 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 15 Jul 2021 18:07:06 +0200
Subject: perf probe: Fix dso->nsinfo refcounting

From: Riccardo Mancini <rickyman7@gmail.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@gmail.com>
Fixes: 544abd44c7064c8a ("perf probe: Allow placing uprobes in alternate namespaces.")
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Krister Johansen <kjlx@templeofstupid.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.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@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.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 a78c8d59a555..9cc89a047b15 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -180,8 +180,10 @@ 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