From c95b9e0c7fe1156ed2e3ba83173a27622d6efebe Mon Sep 17 00:00:00 2001
From: Gaurav Singh <gaurav1086@gmail.com>
Date: Mon, 8 Jun 2020 13:18:17 -0300
Subject: [PATCH] perf report: Fix NULL pointer dereference in
 hists__fprintf_nr_sample_events()

commit 11b6e5482e178055ec1f2444b55f2518713809d1 upstream.

The 'evname' variable can be NULL, as it is checked a few lines back,
check it before using.

Fixes: 9e207ddfa207 ("perf report: Show call graph from reference events")
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/
Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 3aaa1463ff75..f063465ee253 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -448,8 +448,7 @@ static size_t hists__fprintf_nr_sample_events(struct hists *hists, struct report
 	if (rep->time_str)
 		ret += fprintf(fp, " (time slices: %s)", rep->time_str);
 
-	if (symbol_conf.show_ref_callgraph &&
-	    strstr(evname, "call-graph=no")) {
+	if (symbol_conf.show_ref_callgraph && evname && strstr(evname, "call-graph=no")) {
 		ret += fprintf(fp, ", show reference callgraph");
 	}
 
-- 
2.27.0