Commit 85e40b05 authored Feb 26, 2015 by Juergen Gross Committed by David Vrabel Mar 06, 2015

xen/events: avoid NULL pointer dereference in dom0 on large machines



Using the pvops kernel a NULL pointer dereference was detected on a
large machine (144 processors) when booting as dom0 in
evtchn_fifo_unmask() during assignment of a pirq.

The event channel in question was the first to need a new entry in
event_array[] in events_fifo.c. Unfortunately xen_irq_info_pirq_setup()
is called with evtchn being 0 for a new pirq and the real event channel
number is assigned to the pirq only during __startup_pirq().

It is mandatory to call xen_evtchn_port_setup() after assigning the
event channel number to the pirq to make sure all memory needed for the
event channel is allocated.

Signed-off-by: Juergen Gross <jgross@suse.com>
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

parent 604b91fe

drivers/xen/events/events_base.c

+12 −6

Original line number	Diff line number	Diff line
		@@ -526,20 +526,26 @@ static unsigned int __startup_pirq(unsigned int irq)
		pirq_query_unmask(irq);

		rc = set_evtchn_to_irq(evtchn, irq);
		if (rc != 0) {
		pr_err("irq%d: Failed to set port to irq mapping (%d)\n",
		irq, rc);
		xen_evtchn_close(evtchn);
		return 0;
		}
		if (rc)
		goto err;

		bind_evtchn_to_cpu(evtchn, 0);
		info->evtchn = evtchn;

		rc = xen_evtchn_port_setup(info);
		if (rc)
		goto err;

		out:
		unmask_evtchn(evtchn);
		eoi_pirq(irq_get_irq_data(irq));

		return 0;

		err:
		pr_err("irq%d: Failed to set port to irq mapping (%d)\n", irq, rc);
		xen_evtchn_close(evtchn);
		return 0;
		}

		static unsigned int startup_pirq(struct irq_data *data)