From 0f61e86bcc0b3ca51b45ae01fbdfdfea0c0b7fe7 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()

[ Upstream commit 11b6e5482e178055ec1f2444b55f2518713809d1 ]

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: Sasha Levin <sashal@kernel.org>
---
 tools/perf/builtin-report.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 0abca8783bb3..78485edb9467 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -341,8 +341,7 @@ static size_t hists__fprintf_nr_sample_events(struct hists *hists, struct report
 	if (evname != NULL)
 		ret += fprintf(fp, " of event '%s'", evname);
 
-	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");
 	}