From: Kris Shannon <kris@shannon.id.au>
To: Linux Kernel List <linux-kernel@vger.kernel.org>
Subject: [PATCH] Fix kernel NULL pointer dereference in xen-blkfront
Date: Mon, 2 Mar 2009 19:47:37 +1100 [thread overview]
Message-ID: <e51f4f550903020047m7f110039v48bcac6a345f1fd6@mail.gmail.com> (raw)
When booting Xen Dom0 on a pre-release 3.2.1 hypervisor the system Oopses on a
"Unable to handle kernel NULL pointer dereference" in xenwatch.
>From the backtrace it looks like backend_changed is calling bdget_disk
with a NULL pointer. Checking for NULL and returning ENODEV instead
allows the kernel to boot.
---
drivers/block/xen-blkfront.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index f2fff5799ddf0fe1b41909b64d606d..3e2ab6d53adaeb70efa12f0a1f33bb 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -905,6 +905,8 @@ static void backend_changed(struct xenbus_device *dev,
break;
case XenbusStateClosing:
+ if (info->gd == NULL)
+ xenbus_dev_fatal(dev, -ENODEV, "gd is NULL");
bd = bdget_disk(info->gd, 0);
if (bd == NULL)
xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
--
1.6.1.3
next reply other threads:[~2009-03-02 8:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-02 8:47 Kris Shannon [this message]
2009-03-03 21:59 ` Jeremy Fitzhardinge
2009-03-04 10:16 ` Jens Axboe
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