| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.14 54/79] xen/events: avoid NULL pointer dereference in dom0 on large machines | Date | Tue, 24 Mar 2015 16:46:05 +0100 |
| |
3.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Juergen Gross <jgross@suse.com>
commit 85e40b0539b24518c8bdf63e2605c8522377d00f upstream.
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> Signed-off-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/xen/events/events_base.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
--- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -547,20 +547,26 @@ static unsigned int __startup_pirq(unsig 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)
|