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    Subject[PATCH 5.10 035/167] perf probe: Fix dso->nsinfo refcounting
    Date
    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 8eae2afff71a..07db6cfad65b 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


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