accounts/abi: harden unpacking against malicious input

accounts/abi/unpack_test.go

@@ -683,3 +683,73 @@ func TestUnmarshal(t *testing.T) {
 		t.Fatal("expected error:", err)
 	}
 }
+
+func TestOOMMaliciousInput(t *testing.T) {
+	oomTests := []unpackTest{
+		{
+			def: `[{"type": "uint8[]"}]`,
+			enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset
+				"0000000000000000000000000000000000000000000000000000000000000003" + // num elems
+				"0000000000000000000000000000000000000000000000000000000000000001" + // elem 1
+				"0000000000000000000000000000000000000000000000000000000000000002", // elem 2
+		},
+		{ // Length larger than 64 bits
+			def: `[{"type": "uint8[]"}]`,
+			enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset
+				"00ffffffffffffffffffffffffffffffffffffffffffffff0000000000000002" + // num elems
+				"0000000000000000000000000000000000000000000000000000000000000001" + // elem 1
+				"0000000000000000000000000000000000000000000000000000000000000002", // elem 2
+		},
+		{ // Offset very large (over 64 bits)
+			def: `[{"type": "uint8[]"}]`,
+			enc: "00ffffffffffffffffffffffffffffffffffffffffffffff0000000000000020" + // offset
+				"0000000000000000000000000000000000000000000000000000000000000002" + // num elems
+				"0000000000000000000000000000000000000000000000000000000000000001" + // elem 1
+				"0000000000000000000000000000000000000000000000000000000000000002", // elem 2
+		},
+		{ // Offset very large (below 64 bits)
+			def: `[{"type": "uint8[]"}]`,
+			enc: "0000000000000000000000000000000000000000000000007ffffffffff00020" + // offset
+				"0000000000000000000000000000000000000000000000000000000000000002" + // num elems
+				"0000000000000000000000000000000000000000000000000000000000000001" + // elem 1
+				"0000000000000000000000000000000000000000000000000000000000000002", // elem 2
+		},
+		{ // Offset negative (as 64 bit)
+			def: `[{"type": "uint8[]"}]`,
+			enc: "000000000000000000000000000000000000000000000000f000000000000020" + // offset
+				"0000000000000000000000000000000000000000000000000000000000000002" + // num elems
+				"0000000000000000000000000000000000000000000000000000000000000001" + // elem 1
+				"0000000000000000000000000000000000000000000000000000000000000002", // elem 2
+		},
+
+		{ // Negative length
+			def: `[{"type": "uint8[]"}]`,
+			enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset
+				"000000000000000000000000000000000000000000000000f000000000000002" + // num elems
+				"0000000000000000000000000000000000000000000000000000000000000001" + // elem 1
+				"0000000000000000000000000000000000000000000000000000000000000002", // elem 2
+		},
+		{ // Very large length
+			def: `[{"type": "uint8[]"}]`,
+			enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset
+				"0000000000000000000000000000000000000000000000007fffffffff000002" + // num elems
+				"0000000000000000000000000000000000000000000000000000000000000001" + // elem 1
+				"0000000000000000000000000000000000000000000000000000000000000002", // elem 2
+		},
+	}
+	for i, test := range oomTests {
+		def := fmt.Sprintf(`[{ "name" : "method", "outputs": %s}]`, test.def)
+		abi, err := JSON(strings.NewReader(def))
+		if err != nil {
+			t.Fatalf("invalid ABI definition %s: %v", def, err)
+		}
+		encb, err := hex.DecodeString(test.enc)
+		if err != nil {
+			t.Fatalf("invalid hex: %s" + test.enc)
+		}
+		_, err = abi.Methods["method"].Outputs.UnpackValues(encb)
+		if err == nil {
+			t.Fatalf("Expected error on malicious input, test %d", i)
+		}
+	}
+}