xen/blkback: don't call vbd_size() if bd_disk is NULL

...because vbd_size() dereferences bd_disk if bd_part is NULL.

Signed-off-by: Laszlo Ersek<lersek@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 34570823355b..6cc0db1bf522 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -357,14 +357,13 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
         }
 
         vbd->bdev = bdev;
-        vbd->size = vbd_sz(vbd);
-
         if (vbd->bdev->bd_disk == NULL) {
                 DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",
                         vbd->pdevice);
                 xen_vbd_free(vbd);
                 return -ENOENT;
         }
+        vbd->size = vbd_sz(vbd);
 
         if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
                 vbd->type |= VDISK_CDROM;