From a1a15ac5f9aeee521c048a88fc1aec848e623de7 Mon Sep 17 00:00:00 2001 From: Kris Shannon Date: Mon, 2 Mar 2009 19:47:37 +1100 Subject: [PATCH] Fix kernel NULL pointer dereference in xen-blkfront 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 file changed, 2 insertions(+) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index b6c8ce25435..8f905089b72 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -977,6 +977,8 @@ 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"); -- 2.20.1