[Xen-devel] [PATCH] xen-blkfront: avoid NULL de-reference in CDROM ioctl handling

["Jan Beulich" <JBeulich@xxxxxxxx>]

The ioctl can be called prior to full device setup having completed.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 drivers/block/xen-blkfront.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- 4.7-rc6-xen.orig/drivers/block/xen-blkfront.c
+++ 4.7-rc6-xen/drivers/block/xen-blkfront.c
@@ -496,12 +496,10 @@ static int blkif_ioctl(struct block_devi
                                return -EFAULT;
                return 0;
 
-       case CDROM_GET_CAPABILITY: {
-               struct gendisk *gd = info->gd;
-               if (gd->flags & GENHD_FL_CD)
+       case CDROM_GET_CAPABILITY:
+               if (info->gd && (info->gd->flags & GENHD_FL_CD))
                        return 0;
                return -EINVAL;
-       }
 
        default:
                /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",




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