linux-kernel - Re: [PATCH v1] perf pmu: Avoid uninitialized use of alias->str

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Message-ID: <ZO9ktixQq0Mq2PHU@kernel.org>
Date:   Wed, 30 Aug 2023 12:48:06 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Ian Rogers <irogers@...gle.com>,
        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>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        James Clark <james.clark@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sumanth Korikkar <sumanthk@...ux.ibm.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Jing Zhang <renyu.zj@...ux.alibaba.com>
Subject: Re: [PATCH v1] perf pmu: Avoid uninitialized use of alias->str

Em Tue, Aug 29, 2023 at 07:23:58PM -0700, Namhyung Kim escreveu:
> Hi Ian,
> 
> On Tue, Aug 29, 2023 at 5:05 PM Ian Rogers <irogers@...gle.com> wrote:
> >
> > alias is allocated with malloc allowing uninitialized memory to be
> > accessed. The initialization of str was moved late after it could have
> > been updated by a JSON event, however, this create a potential for an
> > uninitialized use. Fix this by assigning str to NULL early. Testing on
> > ARM (Raspberry Pi) showed a memory leak in the same code so add a
> > zfree.
> >
> > Fixes: f63a536f03a2 ("perf pmu: Merge JSON events with sysfs at load time")
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> 
> Acked-by: Namhyung Kim <namhyung@...nel.org>

Thanks, applied.

- Arnaldo
 
> Thanks,
> Namhyung
> 
> 
> > ---
> >  tools/perf/util/pmu.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > index cde33e01959a..b3f8f3f1e900 100644
> > --- a/tools/perf/util/pmu.c
> > +++ b/tools/perf/util/pmu.c
> > @@ -532,6 +532,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
> >         if (!alias)
> >                 return -ENOMEM;
> >
> > +       alias->str = NULL;
> >         INIT_LIST_HEAD(&alias->terms);
> >         alias->scale = 1.0;
> >         alias->unit[0] = '\0';
> > @@ -593,6 +594,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
> >                         ret += scnprintf(newval + ret, sizeof(newval) - ret,
> >                                          "%s=%s", term->config, term->val.str);
> >         }
> > +       zfree(&alias->str);
> >         alias->str = strdup(newval);
> >         if (!pe)
> >                 pmu->sysfs_aliases++;
> > --
> > 2.42.0.rc2.253.gd59a3bf2b4-goog
> >

-- 

- Arnaldo