Fix parseTrailer panic

header.go

@@ -2339,9 +2339,15 @@ func (h *ResponseHeader) parse(buf []byte) (int, error) {
 }
 
 func (h *ResponseHeader) parseTrailer(buf []byte) (int, error) {
+	// Skip any 0 length chunk.
 	if buf[0] == '0' {
-		buf = buf[len(strCRLF)+1:]
+		skip := len(strCRLF) + 1
+		if len(buf) < skip {
+			return 0, io.EOF
+		}
+		buf = buf[skip:]
 	}
+
 	var s headerScanner
 	s.b = buf
 	s.disableNormalizing = h.disableNormalizing
@@ -2392,9 +2398,15 @@ func (h *RequestHeader) parse(buf []byte) (int, error) {
 }
 
 func (h *RequestHeader) parseTrailer(buf []byte) (int, error) {
+	// Skip any 0 length chunk.
 	if buf[0] == '0' {
-		buf = buf[len(strCRLF)+1:]
+		skip := len(strCRLF) + 1
+		if len(buf) < skip {
+			return 0, io.EOF
+		}
+		buf = buf[skip:]
 	}
+
 	var s headerScanner
 	s.b = buf
 	s.disableNormalizing = h.disableNormalizing

http_test.go

@@ -16,6 +16,16 @@ import (
 	"github.com/valyala/bytebufferpool"
 )
 
+func TestInvalidTrailers(t *testing.T) {
+	t.Parallel()
+
+	br := bufio.NewReader(bytes.NewReader([]byte{0x20, 0x30, 0x0a, 0x54, 0x72, 0x61, 0x6e, 0x73, 0x66, 0x65, 0x72, 0x2d, 0x45, 0x6e, 0x63, 0x6f, 0x64, 0x69, 0x6e, 0x67, 0x3a, 0xff, 0x0a, 0x0a, 0x30, 0x0d, 0x0a, 0x30}))
+	err := (&Response{}).Read(br)
+	if err == io.EOF {
+		t.Fatal(err)
+	}
+}
+
 func TestResponseEmptyTransferEncoding(t *testing.T) {
 	t.Parallel()