Jeremy Fitzhardinge
2009-Mar-03 21:59 UTC
[Xen-devel] Re: [PATCH] Fix kernel NULL pointer dereference in xen-blkfront
Kris Shannon wrote:> 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. >Thanks, applied. (BTW, please cc: me and xen-devel for Xen-related reports.) Jens: could you pull this; I think this is probably -rc material. This crash just started happening, so I guess its a side-effect of some core kernel change. The following changes since commit c7241227f61ca6606a7fa3555391360d92bd8d9b: Jens Axboe (1): xen/blkfront: use blk_rq_map_sg to generate ring entries are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git xen/frontend/blkfront Kris Shannon (1): Fix kernel NULL pointer dereference in xen-blkfront drivers/block/xen-blkfront.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) Thanks, J> --- > 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"); >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel