http2: fix crash in Transport on double Read of invalid gzip Response.Body
This old code was buggy:
type gzipReader struct {
body io.ReadCloser // underlying Response.Body
zr io.Reader // lazily-initialized gzip reader
}
func (gz *gzipReader) Read(p []byte) (n int, err error) {
if gz.zr == nil {
gz.zr, err = gzip.NewReader(gz.body)
if err != nil {
return 0, err
}
}
return gz.zr.Read(p)
}
If a Read on a gzipped Response.Body (of type *http2.gzipReader)
resulted in gzip.NewReader returning an error, gzipReader assigned
a *gzip.Reader-typed nil value to the gz.zr interface value.
On a subsequent Read, gz.zr would not be equal to ==, because it was
actually equal to (type *gzip.Reader, nil), and then zr.Read would call
(*gzip.Reader).Read with a nil receiver and explode.
Debugged internally. (http://go/http2gzipbug)
Change-Id: Icba040ace8ffac3536e5e7ade6695c7660838ca1
diff --git a/http2/transport.go b/http2/transport.go
index 0aaa067..c3a1bdb 100644
--- a/http2/transport.go
+++ b/http2/transport.go
@@ -1723,13 +1723,18 @@
// call gzip.NewReader on the first call to Read
type gzipReader struct {
body io.ReadCloser // underlying Response.Body
- zr io.Reader // lazily-initialized gzip reader
+ zr *gzip.Reader // lazily-initialized gzip reader
+ zerr error // sticky error
}
func (gz *gzipReader) Read(p []byte) (n int, err error) {
+ if gz.zerr != nil {
+ return 0, gz.zerr
+ }
if gz.zr == nil {
gz.zr, err = gzip.NewReader(gz.body)
if err != nil {
+ gz.zerr = err
return 0, err
}
}
diff --git a/http2/transport_test.go b/http2/transport_test.go
index e9b89f7..3942873 100644
--- a/http2/transport_test.go
+++ b/http2/transport_test.go
@@ -1660,3 +1660,20 @@
}
}
}
+
+// Tests that gzipReader doesn't crash on a second Read call following
+// the first Read call's gzip.NewReader returning an error.
+func TestGzipReader_DoubleReadCrash(t *testing.T) {
+ gz := &gzipReader{
+ body: ioutil.NopCloser(strings.NewReader("0123456789")),
+ }
+ var buf [1]byte
+ n, err1 := gz.Read(buf[:])
+ if n != 0 || !strings.Contains(fmt.Sprint(err1), "invalid header") {
+ t.Fatalf("Read = %v, %v; want 0, invalid header", n, err1)
+ }
+ n, err2 := gz.Read(buf[:])
+ if n != 0 || err2 != err1 {
+ t.Fatalf("second Read = %v, %v; want 0, %v", n, err2, err1)
+ }
+}
