acpi: add Makefile target for fuzzing and AML parser fuzzer

The fuzzer can be invoked by running: "make test-fuzz". The AML parser
test suite has been augmented with a special "TestParserCrashers"
function that can be used to replay corpuses identified by go-fuzz as
causing parser crashes.

The test can be invoked as:

go test -v -run TestParserCrashers -aml-replace-crashers-from
$BUILD/fuzz/corpus/src_gopheros_device_acpi_aml/crashers

where $BUILD is the output directory (default: build/) defined in the
Makefile.

src/gopheros/device/acpi/aml/parser_test.go

@@ -16,9 +16,41 @@ import (
 )
 
 var (
-	regenExpFiles = flag.Bool("aml-regenerate-parser-exp-files", false, "Regenerate the expected output files for AML parser tests against real AML files")
+	regenExpFiles      = flag.Bool("aml-regenerate-parser-exp-files", false, "Regenerate the expected output files for AML parser tests against real AML files")
+	replayCrashersFrom = flag.String("aml-replay-crashers-from", "", "Replay go-fuzz generated crasher files from this folder")
 )
 
+// TestParserCrashers scans through the crasher corpus generated by go-fuzz and
+// pipes each corpus through the AML parser.
+func TestParserCrashers(t *testing.T) {
+	if *replayCrashersFrom == "" {
+		t.Skip("-aml-replay-crashers-from not specified; skipping")
+		return
+	}
+
+	fuzzFiles, err := filepath.Glob(filepath.Join(*replayCrashersFrom, "*"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, fuzzFile := range fuzzFiles {
+		// corpus files lack an extension
+		if filepath.Ext(fuzzFile) != "" {
+			continue
+		}
+
+		data, err := ioutil.ReadFile(fuzzFile)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		t.Logf("trying to parse crash corpus: %q", fuzzFile)
+		p, resolver := parserForMockPayload(t, data)
+		_ = p.ParseAML(0, "DSDT", resolver.LookupTable("DSDT"))
+	}
+
+}
+
 func TestParser(t *testing.T) {
 	flag.Parse()