From 7a676822c292e3f405fc21ac0897393d715a12ea Mon Sep 17 00:00:00 2001
From: Nikola Jokic <jokicnikola07@gmail.com>
Date: Sat, 8 Oct 2022 17:00:06 +0200
Subject: [PATCH] x/net/http2: gzipReader will reset zr to nil after closing
 body

The existing implementation does not reset gz.zr. After Close,
gzipReader closes underlying response body but buffered data can still
be read.

gzipReader on Close sets the gz.zerr to fs.ErrClosed so next Read after
Close will return it immediately.

Fixes golang/go#56020

Change-Id: I8a31e4c65656b9abc3023855b8e04342e1e77cbb
Reviewed-on: https://go-review.googlesource.com/c/net/+/440555
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
---
 http2/transport.go      |  7 ++++++-
 http2/transport_test.go | 24 ++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/http2/transport.go b/http2/transport.go
index e78804b22..5a179b669 100644
--- a/http2/transport.go
+++ b/http2/transport.go
@@ -16,6 +16,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"log"
 	"math"
 	mathrand "math/rand"
@@ -2985,7 +2986,11 @@ func (gz *gzipReader) Read(p []byte) (n int, err error) {
 }
 
 func (gz *gzipReader) Close() error {
-	return gz.body.Close()
+	if err := gz.body.Close(); err != nil {
+		return err
+	}
+	gz.zerr = fs.ErrClosed
+	return nil
 }
 
 type errorReader struct{ err error }
diff --git a/http2/transport_test.go b/http2/transport_test.go
index 67afb57c3..c7389119f 100644
--- a/http2/transport_test.go
+++ b/http2/transport_test.go
@@ -7,6 +7,7 @@ package http2
 import (
 	"bufio"
 	"bytes"
+	"compress/gzip"
 	"context"
 	"crypto/tls"
 	"encoding/hex"
@@ -14,6 +15,7 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"io/fs"
 	"io/ioutil"
 	"log"
 	"math/rand"
@@ -2503,6 +2505,28 @@ func TestGzipReader_DoubleReadCrash(t *testing.T) {
 	}
 }
 
+func TestGzipReader_ReadAfterClose(t *testing.T) {
+	body := bytes.Buffer{}
+	w := gzip.NewWriter(&body)
+	w.Write([]byte("012345679"))
+	w.Close()
+	gz := &gzipReader{
+		body: ioutil.NopCloser(&body),
+	}
+	var buf [1]byte
+	n, err := gz.Read(buf[:])
+	if n != 1 || err != nil {
+		t.Fatalf("first Read = %v, %v; want 1, nil", n, err)
+	}
+	if err := gz.Close(); err != nil {
+		t.Fatalf("gz Close error: %v", err)
+	}
+	n, err = gz.Read(buf[:])
+	if n != 0 || err != fs.ErrClosed {
+		t.Fatalf("Read after close = %v, %v; want 0, fs.ErrClosed", n, err)
+	}
+}
+
 func TestTransportNewTLSConfig(t *testing.T) {
 	tests := [...]struct {
 		conf *tls.Config