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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>
This commit is contained in:
Juergen Gross 2015-02-26 06:52:05 +01:00 committed by David Vrabel
parent 604b91fee4
commit 85e40b0539
1 changed files with 12 additions and 6 deletions
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18
drivers/xen/events/events_base.c
View File

@ -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)