Avoid nil pointer dereference while creating a container with an empty Config

Signed-off-by: Antonio Murdaca <runcom@linux.com>

api/server/server.go

@@ -658,10 +658,6 @@ func (s *Server) postCommit(version version.Version, w http.ResponseWriter, r *h
 		return err
 	}
 
-	if c == nil {
-		c = &runconfig.Config{}
-	}
-
 	containerCommitConfig := &daemon.ContainerCommitConfig{
 		Pause:   pause,
 		Repo:    r.Form.Get("repo"),

builder/job.go

@@ -221,6 +221,10 @@ func Commit(d *daemon.Daemon, name string, c *daemon.ContainerCommitConfig) (str
 		return "", err
 	}
 
+	if c.Config == nil {
+		c.Config = &runconfig.Config{}
+	}
+
 	newConfig, err := BuildFromConfig(d, c.Config, c.Changes)
 	if err != nil {
 		return "", err

daemon/create.go

@@ -15,6 +15,10 @@ import (
 )
 
 func (daemon *Daemon) ContainerCreate(name string, config *runconfig.Config, hostConfig *runconfig.HostConfig) (string, []string, error) {
+	if config == nil {
+		return "", nil, fmt.Errorf("Config cannot be empty in order to create a container")
+	}
+
 	warnings, err := daemon.verifyHostConfig(hostConfig)
 	if err != nil {
 		return "", warnings, err

integration-cli/docker_api_containers_test.go

@@ -836,6 +836,19 @@ func (s *DockerSuite) TestContainerApiCreate(c *check.C) {
 	}
 }
 
+func (s *DockerSuite) TestContainerApiCreateEmptyConfig(c *check.C) {
+	config := map[string]interface{}{}
+
+	status, b, err := sockRequest("POST", "/containers/create", config)
+	c.Assert(err, check.IsNil)
+	c.Assert(status, check.Equals, http.StatusInternalServerError)
+
+	expected := "Config cannot be empty in order to create a container\n"
+	if body := string(b); body != expected {
+		c.Fatalf("Expected to get %q, got %q", expected, body)
+	}
+}
+
 func (s *DockerSuite) TestContainerApiCreateWithHostName(c *check.C) {
 	hostName := "test-host"
 	config := map[string]interface{}{

runconfig/config.go

@@ -143,6 +143,10 @@ func (c ContainerConfigWrapper) HostConfig() *HostConfig {
 	return c.hostConfigWrapper.GetHostConfig()
 }
 
+// DecodeContainerConfig decodes a json encoded config into a ContainerConfigWrapper
+// struct and returns both a Config and an HostConfig struct
+// Be aware this function is not checking whether the resulted structs are nil,
+// it's your business to do so
 func DecodeContainerConfig(src io.Reader) (*Config, *HostConfig, error) {
 	decoder := json.NewDecoder(src)