Add support for decoding ENDBR32/64 instructions (#1416)

pkg/internal/goexec/instructions_amd64.go

@@ -6,10 +6,31 @@ import (
 	"golang.org/x/arch/x86/x86asm"
 )
 
+const endbrSize = 4
+
+func isENDBRXX(data []uint8) bool {
+	if len(data) < endbrSize {
+		return false
+	}
+
+	return data[0] == 0xF3 &&
+		data[1] == 0x0F &&
+		data[2] == 0x1E &&
+		(data[3] == 0xFA || data[3] == 0xFB)
+}
+
 func findReturnOffssets(baseOffset uint64, data []byte) ([]uint64, error) {
 	var returnOffsets []uint64
 	index := 0
 	for index < len(data) {
+
+		// FIXME remove this once x86asm is able to recognize and decode
+		// ENDBR64
+		if isENDBRXX(data[index:]) {
+			index += endbrSize
+			continue
+		}
+
 		instruction, err := x86asm.Decode(data[index:], 64)
 		if err != nil {
 			return nil, fmt.Errorf("failed to decode x64 instruction at offset %d: %w", index, err)

pkg/internal/goexec/instructions_test.go

@@ -0,0 +1,52 @@
+package goexec
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var prog = []uint8{
+	0xf3, 0x0f, 0x1e, 0xfa, // endbr64
+	0xf3, 0x0f, 0x1e, 0xfb, // endbr32
+	0x55,
+	0x48, 0x89, 0xe5,
+	0x48, 0x83, 0xec, 0x10,
+	0x64, 0x48, 0x8b, 0x04, 0x25, 0x28, 0x00,
+	0x00, 0x00,
+	0x48, 0x89, 0x45, 0xf8,
+	0x31, 0xc0,
+	0x85, 0xd2,
+	0x78, 0x24,
+	0x48, 0x8d, 0x4d, 0xf0,
+	0x48, 0x63, 0xd2,
+	0xe8, 0x25, 0xfd, 0xff, 0xff,
+	0x85, 0xc0,
+	0x7e, 0x03,
+	0x8b, 0x45, 0xf0,
+	0x48, 0x8b, 0x55, 0xf8,
+	0x64, 0x48, 0x2b, 0x14, 0x25, 0x28, 0x00,
+	0x00, 0x00,
+	0x75, 0x3c,
+	0xc9,
+	0xc3, // ret
+	0xff, 0x15, 0x2f, 0x1a, 0x0b, 0x00,
+	0x48, 0x8d, 0x15, 0x28, 0xfd, 0x08, 0x00,
+	0xbe, 0x18, 0x09, 0x00, 0x00,
+	0x48, 0x8d, 0x3d, 0x82, 0x4f, 0x08, 0x00,
+	0xff, 0x15, 0x4e, 0x1d, 0x0b, 0x00,
+	0x31, 0xc0,
+	0x31, 0xd2,
+	0xbe, 0x0f, 0x01, 0x00, 0x00,
+	0xbf, 0x14, 0x00, 0x00, 0x00,
+	0xff, 0x15, 0x72, 0x1c, 0x0b, 0x00,
+	0xb8, 0xff, 0xff, 0xff, 0xff,
+	0xeb, 0xb5,
+	0xff, 0x15, 0xb5, 0x21, 0x0b, 0x00,
+}
+
+func TestFindReturnOffsets(t *testing.T) {
+	offsets, err := findReturnOffssets(0, prog)
+	require.NoError(t, err)
+	require.Contains(t, offsets, uint64(0x46))
+}