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Message-ID: <CAM9d7ciW1wF7YGszv4KQ_KRUhCeBVynQsuRi2+NoRAYgy3xsRw@mail.gmail.com>
Date: Wed, 12 Oct 2022 09:20:10 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...hat.com>, Ian Rogers <irogers@...gle.com>,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-perf-users <linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH 1/2] perf intel-pt: Fix segfault in intel_pt_print_info()
with uClibc
Hi Adrian,
On Wed, Oct 12, 2022 at 1:23 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> uClibc segfaulted because NULL was passed as the format to fprintf().
Sounds like glibc has a NULL check in fprintf().
>
> That happened because one of the format strings was missing and
> intel_pt_print_info() didn't check that before calling fprintf().
>
> Add the missing format string, and check format is not NULL before calling
> fprintf().
>
> Fixes: 11fa7cb86b56 ("perf tools: Pass Intel PT information for decoding MTC and CYC")
> Cc: stable@...r.kernel.org
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Acked-by: Namhyung Kim <namhyung@...nel.org>
Thanks,
Namhyung
> ---
> tools/perf/util/intel-pt.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index b34cb3dec1aa..e3548ddef254 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -4046,6 +4046,7 @@ static const char * const intel_pt_info_fmts[] = {
> [INTEL_PT_SNAPSHOT_MODE] = " Snapshot mode %"PRId64"\n",
> [INTEL_PT_PER_CPU_MMAPS] = " Per-cpu maps %"PRId64"\n",
> [INTEL_PT_MTC_BIT] = " MTC bit %#"PRIx64"\n",
> + [INTEL_PT_MTC_FREQ_BITS] = " MTC freq bits %#"PRIx64"\n",
> [INTEL_PT_TSC_CTC_N] = " TSC:CTC numerator %"PRIu64"\n",
> [INTEL_PT_TSC_CTC_D] = " TSC:CTC denominator %"PRIu64"\n",
> [INTEL_PT_CYC_BIT] = " CYC bit %#"PRIx64"\n",
> @@ -4060,8 +4061,12 @@ static void intel_pt_print_info(__u64 *arr, int start, int finish)
> if (!dump_trace)
> return;
>
> - for (i = start; i <= finish; i++)
> - fprintf(stdout, intel_pt_info_fmts[i], arr[i]);
> + for (i = start; i <= finish; i++) {
> + const char *fmt = intel_pt_info_fmts[i];
> +
> + if (fmt)
> + fprintf(stdout, fmt, arr[i]);
> + }
> }
>
> static void intel_pt_print_info_str(const char *name, const char *str)
> --
> 2.25.1
>
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