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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Adrian Hunter <adrian.hunter@intel.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@kernel.org>,
        Kan Liang <kan.liang@intel.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Gaurav Singh <gaurav1086@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 106/136] perf report: Fix NULL pointer dereference in hists__fprintf_nr_sample_events()
Date:   Tue, 23 Jun 2020 21:59:22 +0200
Message-Id: <20200623195309.009008965@linuxfoundation.org>
In-Reply-To: <20200623195303.601828702@linuxfoundation.org>
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From: Gaurav Singh <gaurav1086@gmail.com>

[ 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 429c3e140dc32..35a10b5985447 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -401,8 +401,7 @@ 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");
 	}
 
-- 
2.25.1