linux-kernel - Re: [PATCH] perf: cs-etm: Fix segfault in dso lookup

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Date:   Tue, 18 Apr 2023 12:26:04 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     James Clark <james.clark@....com>
Cc:     linux-perf-users@...r.kernel.org,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf: cs-etm: Fix segfault in dso lookup

Em Tue, Apr 18, 2023 at 03:12:03PM +0100, James Clark escreveu:
> map__dso() is called before thread__find_map() which always results in a
> null pointer dereference. Fix it by finding first, then checking if it
> exists.
> 
> Fixes: 63df0e4bc368 ("perf map: Add accessor for dso")

Thanks, applied, checking if another such pattern slipped by in that
cset.

- Arnaldo

> Signed-off-by: James Clark <james.clark@....com>
> ---
>  tools/perf/util/cs-etm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index 103865968700..8dd81ddd9e4e 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -885,9 +885,11 @@ static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u8 trace_chan_id,
>  		thread = etmq->etm->unknown_thread;
>  	}
>  
> -	dso = map__dso(al.map);
> +	if (!thread__find_map(thread, cpumode, address, &al))
> +		return 0;
>  
> -	if (!thread__find_map(thread, cpumode, address, &al) || !dso)
> +	dso = map__dso(al.map);
> +	if (!dso)
>  		return 0;
>  
>  	if (dso->data.status == DSO_DATA_STATUS_ERROR &&
> -- 
> 2.34.1
> 

-- 

- Arnaldo