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SubjectRe: [PATCH] xen: avoid NULL pointer dereference in dom0 on large machines
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On 02/26/2015 06:52 AM, Juergen Gross wrote:
> 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>
> ---
> 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 b4bca2d..70fba97 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)
>



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