linux-kernel - [PATCH 02/31] perf parse-events: Add defensive NULL check

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Date:   Fri,  3 Apr 2020 11:54:14 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Ian Rogers <irogers@...gle.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        John Garry <john.garry@...wei.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephane Eranian <eranian@...gle.com>,
        clang-built-linux@...glegroups.com,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 02/31] perf parse-events: Add defensive NULL check

From: Ian Rogers <irogers@...gle.com>

Terms may have a NULL config in which case a strcmp will SEGV. This can
be reproduced with:

  perf stat -e '*/event=?,nr/' sleep 1

Add a NULL check to avoid this. This was caught by LLVM's libfuzzer.

Signed-off-by: Ian Rogers <irogers@...gle.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Jin Yao <yao.jin@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: John Garry <john.garry@...wei.com>
Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: clang-built-linux@...glegroups.com
Link: http://lore.kernel.org/lkml/20200325164022.41385-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/pmu.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 616fbda7c3fc..ef6a63f3d386 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -984,12 +984,11 @@ static int pmu_resolve_param_term(struct parse_events_term *term,
 	struct parse_events_term *t;
 
 	list_for_each_entry(t, head_terms, list) {
-		if (t->type_val == PARSE_EVENTS__TERM_TYPE_NUM) {
-			if (!strcmp(t->config, term->config)) {
-				t->used = true;
-				*value = t->val.num;
-				return 0;
-			}
+		if (t->type_val == PARSE_EVENTS__TERM_TYPE_NUM &&
+		    t->config && !strcmp(t->config, term->config)) {
+			t->used = true;
+			*value = t->val.num;
+			return 0;
 		}
 	}
 
-- 
2.21.1