From 85e40b0539b24518c8bdf63e2605c8522377d00f Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 26 Feb 2015 06:52:05 +0100 Subject: [PATCH] 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 Cc: # 3.14+ Signed-off-by: David Vrabel --- drivers/xen/events/events_base.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index b4bca2d4a7e5..70fba973a107 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -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) -- 2.20.1