[Xen-changelog] [linux-2.6.18-xen] blkfront: avoid NULL de-reference in CDROM ioctl handling

[Xen patchbot-linux-2.6.18-xen <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxxxx>
# Date 1310127827 -3600
# Node ID 73e47d0fdb100e92233ee9142964c54fa2084795
# Parent  d1a48f331c67d2667c91bc24f314abbdaba40e72
blkfront: avoid NULL de-reference in CDROM ioctl handling

Just like already done in the default case, for CDROM_GET_CAPABILITY
info->gd should not be blindly de-referenced, as the ioctl can be
called prior to full device setup having completed.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---


diff -r d1a48f331c67 -r 73e47d0fdb10 drivers/xen/blkfront/blkfront.c
--- a/drivers/xen/blkfront/blkfront.c   Fri Jul 08 13:18:31 2011 +0100
+++ b/drivers/xen/blkfront/blkfront.c   Fri Jul 08 13:23:47 2011 +0100
@@ -566,12 +566,11 @@
                                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:
                if (info->mi && info->gd) {
                        switch (info->mi->major) {

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