huff0: fix handling errors in Decompress1X asm (#604)

Add a regression test.

huff0/_generate/gen.go

@@ -495,6 +495,8 @@ func (d decompress1x) generateProcedure(name string) {
 		MOVQ(I64(-1), tmp)
 		Store(tmp, ctx.Field("decoded"))
 	}
+
+	RET()
 }
 
 func (d decompress1x) decompress(id int, br *bitReader, peekBits, dt reg.GPVirtual, out reg.Register) {

huff0/decompress_amd64.s

@@ -765,6 +765,7 @@ error_max_decoded_size_exeeded:
 	MOVQ ctx+0(FP), AX
 	MOVQ $-1, CX
 	MOVQ CX, 40(AX)
+	RET
 
 // func decompress1x_main_loop_bmi2(ctx *decompress1xContext)
 // Requires: BMI2
@@ -861,3 +862,4 @@ error_max_decoded_size_exeeded:
 	MOVQ ctx+0(FP), AX
 	MOVQ $-1, CX
 	MOVQ CX, 40(AX)
+	RET

huff0/decompress_test.go

@@ -3,7 +3,10 @@ package huff0
 import (
 	"bytes"
 	"fmt"
+	"io/ioutil"
 	"testing"
+
+	"github.com/klauspost/compress/zip"
 )
 
 func TestDecompress1X(t *testing.T) {
@@ -96,6 +99,43 @@ func TestDecompress1X(t *testing.T) {
 	}
 }
 
+func TestDecompress1XRegression(t *testing.T) {
+	data, err := ioutil.ReadFile("testdata/decompress1x_regression.zip")
+	if err != nil {
+		t.Fatal(err)
+	}
+	zr, err := zip.NewReader(bytes.NewReader(data), int64(len(data)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, tt := range zr.File {
+		if tt.UncompressedSize64 == 0 {
+			continue
+		}
+		rc, err := tt.Open()
+		if err != nil {
+			t.Fatal(err)
+		}
+		data, err := ioutil.ReadAll(rc)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		t.Run(tt.Name, func(t *testing.T) {
+			s, rem, err := ReadTable(data, nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			_, err = s.Decompress1X(rem)
+			if err == nil {
+				t.Fatal("expected error to be returned")
+			}
+
+			t.Logf("returned error: %s", err)
+		})
+	}
+}
+
 func TestDecompress4X(t *testing.T) {
 	for _, test := range testfiles {
 		t.Run(test.name, func(t *testing.T) {