[PATCH 4.19 221/229] perf intel-pt: Fix segfault in intel_pt_print_info() with uClibc

[Greg Kroah-Hartman]

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
@@ -2373,6 +2373,7 @@ 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",
@@ -2387,8 +2388,12 @@ 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)