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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Sun, 8 Oct 2023 22:51:33 -0700
Message-ID: <CAM9d7chmVRrFgEZMYk3EWG+1wjXqLC3suu-xrX64hmfBSAFi0A@mail.gmail.com>
Subject: Re: [PATCH v2 05/18] perf bench uprobe: Fix potential use of memory
 after free
To:     Ian Rogers <irogers@google.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Yicong Yang <yangyicong@hisilicon.com>,
        Jonathan Cameron <jonathan.cameron@huawei.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Ming Wang <wangming01@loongson.cn>,
        Huacai Chen <chenhuacai@kernel.org>,
        Sean Christopherson <seanjc@google.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Yanteng Si <siyanteng@loongson.cn>,
        Yuan Can <yuancan@huawei.com>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        James Clark <james.clark@arm.com>, llvm@lists.linux.dev,
        linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        bpf@vger.kernel.org
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On Thu, Oct 5, 2023 at 4:09 PM Ian Rogers <irogers@google.com> wrote:
>
> Found by clang-tidy:
> ```
> bench/uprobe.c:98:3: warning: Use of memory after it is freed [clang-analyzer-unix.Malloc]
>                 bench_uprobe_bpf__destroy(skel);
> ```
>
> Signed-off-by: Ian Rogers <irogers@google.com>

I'm ok with the change but I think it won't call
bench_uprobe__teardown_bpf_skel() if the setup function
returns a negative value.  Maybe we also need to set the
err in the default case of `switch (bench)` statement.

Thanks,
Namhyung


> ---
>  tools/perf/bench/uprobe.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/tools/perf/bench/uprobe.c b/tools/perf/bench/uprobe.c
> index 914c0817fe8a..5c71fdc419dd 100644
> --- a/tools/perf/bench/uprobe.c
> +++ b/tools/perf/bench/uprobe.c
> @@ -89,6 +89,7 @@ static int bench_uprobe__setup_bpf_skel(enum bench_uprobe bench)
>         return err;
>  cleanup:
>         bench_uprobe_bpf__destroy(skel);
> +       skel = NULL;
>         return err;
>  }
>
> --
> 2.42.0.609.gbb76f46606-goog
>