Limit the read length of ioutil.ReadAll in pkg/credentialprovider

Signed-off-by: Haiyan Meng <haiyanmeng@google.com>

pkg/credentialprovider/azure/azure_acr_helper.go

@@ -47,7 +47,9 @@ package azure
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"net/url"
@@ -178,10 +180,15 @@ func performTokenExchange(
 	}
 
 	var content []byte
-	if content, err = ioutil.ReadAll(exchange.Body); err != nil {
+	limitedReader := &io.LimitedReader{R: exchange.Body, N: maxReadLength}
+	if content, err = ioutil.ReadAll(limitedReader); err != nil {
 		return "", fmt.Errorf("Www-Authenticate: error reading response from %s", authEndpoint)
 	}
 
+	if limitedReader.N <= 0 {
+		return "", errors.New("the read limit is reached")
+	}
+
 	var authResp acrAuthResponse
 	if err = json.Unmarshal(content, &authResp); err != nil {
 		return "", fmt.Errorf("Www-Authenticate: unable to read response %s", content)

pkg/credentialprovider/azure/azure_credentials.go

@@ -18,6 +18,7 @@ package azure
 
 import (
 	"context"
+	"errors"
 	"io"
 	"io/ioutil"
 	"os"
@@ -38,7 +39,10 @@ import (
 var flagConfigFile = pflag.String("azure-container-registry-config", "",
 	"Path to the file containing Azure container registry configuration information.")
 
-const dummyRegistryEmail = "name@contoso.com"
+const (
+	dummyRegistryEmail = "name@contoso.com"
+	maxReadLength      = 10 * 1 << 20 // 10MB
+)
 
 var containerRegistryUrls = []string{"*.azurecr.io", "*.azurecr.cn", "*.azurecr.de", "*.azurecr.us"}
 
@@ -117,10 +121,14 @@ func parseConfig(configReader io.Reader) (*auth.AzureAuthConfig, error) {
 		return &config, nil
 	}
 
-	configContents, err := ioutil.ReadAll(configReader)
+	limitedReader := &io.LimitedReader{R: configReader, N: maxReadLength}
+	configContents, err := ioutil.ReadAll(limitedReader)
 	if err != nil {
 		return nil, err
 	}
+	if limitedReader.N <= 0 {
+		return nil, errors.New("the read limit is reached")
+	}
 	err = yaml.Unmarshal(configContents, &config)
 	if err != nil {
 		return nil, err

pkg/credentialprovider/config.go

@@ -19,7 +19,9 @@ package credentialprovider
 import (
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"os"
@@ -30,6 +32,10 @@ import (
 	"k8s.io/klog"
 )
 
+const (
+	maxReadLength = 10 * 1 << 20 // 10MB
+)
+
 // DockerConfigJson represents ~/.docker/config.json file info
 // see https://github.com/docker/docker/pull/12009
 type DockerConfigJson struct {
@@ -195,11 +201,16 @@ func ReadUrl(url string, client *http.Client, header *http.Header) (body []byte,
 		}
 	}
 
-	contents, err := ioutil.ReadAll(resp.Body)
+	limitedReader := &io.LimitedReader{R: resp.Body, N: maxReadLength}
+	contents, err := ioutil.ReadAll(limitedReader)
 	if err != nil {
 		return nil, err
 	}
 
+	if limitedReader.N <= 0 {
+		return nil, errors.New("the read limit is reached")
+	}
+
 	return contents, nil
 }