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Message-ID: <ZONsqpxUYAJWjxM1@kernel.org>
Date: Mon, 21 Aug 2023 10:54:50 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Kaige Ye <ye@...ge.org>, peterz@...radead.org, mingo@...hat.com,
mark.rutland@....com, alexander.shishkin@...ux.intel.com,
jolsa@...nel.org, namhyung@...nel.org, adrian.hunter@...el.com,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] perf stat-display: Check if snprintf()'s fmt argument
is NULL
Em Mon, Aug 14, 2023 at 01:24:06PM -0700, Ian Rogers escreveu:
> On Thu, Aug 3, 2023 at 7:10 PM Kaige Ye <ye@...ge.org> wrote:
> >
> > It is undefined behavior to pass NULL as snprintf()'s fmt argument.
> > Here is an example to trigger the problem:
> >
> > $ perf stat --metric-only -x, -e instructions -- sleep 1
> > insn per cycle,
> > Segmentation fault (core dumped)
> >
> > With this patch:
> >
> > $ perf stat --metric-only -x, -e instructions -- sleep 1
> > insn per cycle,
> > ,
> >
> > Signed-off-by: Kaige Ye <ye@...ge.org>
>
> Thanks Kaige!
>
> Reviewed-by: Ian Rogers <irogers@...gle.com>
Thanks, applied.
- Arnaldo
> > ---
> > V1 -> V2: Addressed Ian's comments (Ian Rogers)
> > ---
> > tools/perf/util/stat-display.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> > index 7329b3340..031888545 100644
> > --- a/tools/perf/util/stat-display.c
> > +++ b/tools/perf/util/stat-display.c
> > @@ -578,7 +578,7 @@ static void print_metric_only_csv(struct perf_stat_config *config __maybe_unused
> > if (!valid_only_metric(unit))
> > return;
> > unit = fixunit(tbuf, os->evsel, unit);
> > - snprintf(buf, sizeof buf, fmt, val);
> > + snprintf(buf, sizeof(buf), fmt ?: "", val);
> > ends = vals = skip_spaces(buf);
> > while (isdigit(*ends) || *ends == '.')
> > ends++;
> > @@ -600,7 +600,7 @@ static void print_metric_only_json(struct perf_stat_config *config __maybe_unuse
> > if (!valid_only_metric(unit))
> > return;
> > unit = fixunit(tbuf, os->evsel, unit);
> > - snprintf(buf, sizeof(buf), fmt, val);
> > + snprintf(buf, sizeof(buf), fmt ?: "", val);
> > ends = vals = skip_spaces(buf);
> > while (isdigit(*ends) || *ends == '.')
> > ends++;
> >
> > base-commit: f6b8436bede3e80226e8b2100279c4450c73806a
> > --
> > 2.41.0
> >
--
- Arnaldo
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