From 693d3f8c6ab4c9fed5fe4c5ac5fcb44568fe1638 Mon Sep 17 00:00:00 2001
From: Alexander Larsson <alexl@redhat.com>
Date: Thu, 6 Feb 2014 23:08:17 +0100
Subject: [PATCH] devmapper: Fix MountDevice for non-existing Device

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
---
 graphdriver/devmapper/deviceset.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/graphdriver/devmapper/deviceset.go b/graphdriver/devmapper/deviceset.go
index c1f2f558a..637192dbc 100644
--- a/graphdriver/devmapper/deviceset.go
+++ b/graphdriver/devmapper/deviceset.go
@@ -804,6 +804,9 @@ func (devices *DeviceSet) MountDevice(hash, path string) error {
 	defer devices.Unlock()
 
 	info := devices.Devices[hash]
+	if info == nil {
+		return fmt.Errorf("Unknown device %s", hash)
+	}
 
 	if info.mountCount > 0 {
 		if path != info.mountPath {