linux-kernel - [PATCH] perf tools: avoid reading out of scope array

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Date:   Thu, 17 Oct 2019 10:05:31 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     He Kuang <hekuang@...wei.com>,
        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>,
        Andi Kleen <ak@...ux.intel.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 reading out of scope array

Modify tracepoint name into 2 sys components and assemble at use. This
avoids the sys_name array being out of scope at the point of use.
Bug caught with LLVM's address sanitizer with fuzz generated input of
":cs\1" to parse_events.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/parse-events.y | 36 +++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 48126ae4cd13..28be39a703c9 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -104,7 +104,8 @@ static void inc_group_count(struct list_head *list,
 	struct list_head *head;
 	struct parse_events_term *term;
 	struct tracepoint_name {
-		char *sys;
+		char *sys1;
+		char *sys2;
 		char *event;
 	} tracepoint_name;
 	struct parse_events_array array;
@@ -425,9 +426,19 @@ tracepoint_name opt_event_config
 	if (error)
 		error->idx = @1.first_column;
 
-	if (parse_events_add_tracepoint(list, &parse_state->idx, $1.sys, $1.event,
-					error, $2))
-		return -1;
+        if ($1.sys2) {
+		char sys_name[128];
+		snprintf(&sys_name, sizeof(sys_name), "%s-%s",
+			$1.sys1, $1.sys2);
+		if (parse_events_add_tracepoint(list, &parse_state->idx,
+						sys_name, $1.event,
+						error, $2))
+			return -1;
+        } else
+		if (parse_events_add_tracepoint(list, &parse_state->idx,
+						$1.sys1, $1.event,
+						error, $2))
+			return -1;
 
 	$$ = list;
 }
@@ -435,19 +446,22 @@ tracepoint_name opt_event_config
 tracepoint_name:
 PE_NAME '-' PE_NAME ':' PE_NAME
 {
-	char sys_name[128];
-	struct tracepoint_name tracepoint;
-
-	snprintf(&sys_name, 128, "%s-%s", $1, $3);
-	tracepoint.sys = &sys_name;
-	tracepoint.event = $5;
+	struct tracepoint_name tracepoint = {
+		.sys1 = $1,
+		.sys2 = $3,
+		.event = $5,
+	};
 
 	$$ = tracepoint;
 }
 |
 PE_NAME ':' PE_NAME
 {
-	struct tracepoint_name tracepoint = {$1, $3};
+	struct tracepoint_name tracepoint = {
+		.sys1 = $1,
+		.sys2 = NULL,
+		.event = $3,
+	};
 
 	$$ = tracepoint;
 }
-- 
2.23.0.700.g56cf767bdb-goog