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

Laszlo Ersek · konradwilk · commit 6464920a6e30 · 2011-06-01T09:28:20.000-04:00
...because vbd_size() dereferences bd_disk if bd_part is NULL.

Signed-off-by: Laszlo Ersek&lt;lersek@redhat.com&gt;
Signed-off-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
diff --git 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;

Original file line number	Diff line number	Diff line change
`@@ -357,14 +357,13 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,`
`357`	`357`	`}`
`358`	`358`
`359`	`359`	`vbd->bdev = bdev;`
`360`		`- vbd->size = vbd_sz(vbd);`
`361`		`-`
`362`	`360`	`if (vbd->bdev->bd_disk == NULL) {`
`363`	`361`	`DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",`
`364`	`362`	`vbd->pdevice);`
`365`	`363`	`xen_vbd_free(vbd);`
`366`	`364`	`return -ENOENT;`
`367`	`365`	`}`
	`366`	`+ vbd->size = vbd_sz(vbd);`
`368`	`367`
`369`	`368`	`if (vbd->bdev->bd_disk->flags & GENHD_FL_CD \|\| cdrom)`
`370`	`369`	`vbd->type \|= VDISK_CDROM;`