linux-kernel - [PATCH] perf tools: avoid segv in pmu_resolve_param

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Date:   Mon, 25 Nov 2019 09:41:35 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Jin Yao <yao.jin@...ux.intel.com>,
        John Garry <john.garry@...wei.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Cc:     Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: [PATCH] perf tools: avoid segv in pmu_resolve_param_term

PE_TERMS may set the config to NULL, avoid dereferencing this in
pmu_resolve_param_term. Error detected by LLVM's libFuzzer.
To reproduce the segv run:
$ perf record -e 'm/event=?,time/' ls

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/pmu.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index e8d348988026..1a6e36353407 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -988,13 +988,17 @@ 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)
+			continue;
+
+		if (t->config == NULL && term->config != NULL)
+			continue;
+		else if (strcmp(t->config, term->config))
+			continue;
+
+		t->used = true;
+		*value = t->val.num;
+		return 0;
 	}
 
 	if (verbose > 0)
-- 
2.24.0.432.g9d3f5f5b63-goog