all: add a handful of fuzz targets

Adds simple fuzz targets to archive/tar, archive/zip, compress/gzip,
encoding/json, image/jpeg, image/gif, and image/png.

Second attempt, this time we don't use the archives in testdata when
fuzzing archive/tar, since those are rather memory intensive, and
were crashing a number of builders.

Change-Id: I4828d64fa4763c0d8c980392a6578e4dfd956e13
Reviewed-on: https://go-review.googlesource.com/c/go/+/378174
Trust: Roland Shoemaker <roland@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/src/encoding/json/fuzz_test.go b/src/encoding/json/fuzz_test.go
new file mode 100644
index 0000000000..778664c3e5
--- /dev/null
+++ b/src/encoding/json/fuzz_test.go
@@ -0,0 +1,83 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package json
+
+import (
+	"bytes"
+	"io"
+	"testing"
+)
+
+func FuzzUnmarshalJSON(f *testing.F) {
+	f.Add([]byte(`{
+"object": {
+	"slice": [
+		1,
+		2.0,
+		"3",
+		[4],
+		{5: {}}
+	]
+},
+"slice": [[]],
+"string": ":)",
+"int": 1e5,
+"float": 3e-9"
+}`))
+
+	f.Fuzz(func(t *testing.T, b []byte) {
+		for _, typ := range []func() interface{}{
+			func() interface{} { return new(interface{}) },
+			func() interface{} { return new(map[string]interface{}) },
+			func() interface{} { return new([]interface{}) },
+		} {
+			i := typ()
+			if err := Unmarshal(b, i); err != nil {
+				return
+			}
+
+			encoded, err := Marshal(i)
+			if err != nil {
+				t.Fatalf("failed to marshal: %s", err)
+			}
+
+			if err := Unmarshal(encoded, i); err != nil {
+				t.Fatalf("failed to roundtrip: %s", err)
+			}
+		}
+	})
+}
+
+func FuzzDecoderToken(f *testing.F) {
+	f.Add([]byte(`{
+"object": {
+	"slice": [
+		1,
+		2.0,
+		"3",
+		[4],
+		{5: {}}
+	]
+},
+"slice": [[]],
+"string": ":)",
+"int": 1e5,
+"float": 3e-9"
+}`))
+
+	f.Fuzz(func(t *testing.T, b []byte) {
+		r := bytes.NewReader(b)
+		d := NewDecoder(r)
+		for {
+			_, err := d.Token()
+			if err != nil {
+				if err == io.EOF {
+					break
+				}
+				return
+			}
+		}
+	})
+}