[PATCH 4.14 203/210] perf intel-pt: Fix segfault in intel_pt_print_info() with uClibc

From: Greg Kroah-Hartman
Date: Mon Oct 24 2022 - 08:17:00 EST


From: Adrian Hunter <adrian.hunter@xxxxxxxxx>

commit 5a3d47071f0ced0431ef82a5fb6bd077ed9493db upstream.

uClibc segfaulted because NULL was passed as the format to 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: 11fa7cb86b56d361 ("perf tools: Pass Intel PT information for decoding MTC and CYC")
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20221012082259.22394-2-adrian.hunter@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/perf/util/intel-pt.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -2411,6 +2411,7 @@ static const char * const intel_pt_info_
[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",
@@ -2425,8 +2426,12 @@ static void intel_pt_print_info(u64 *arr
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)