On Wed, 2018-02-28 at 09:19 +0000, Roger Pau Monne wrote: > From: Roger Pau Monne <roger.pau@xxxxxxxxxx> > > [ Upstream commit 910f8befdf5bccf25287d9f1743e3e546bcb7ce0 ] > > Current cleanup in the error path of xen_bind_pirq_msi_to_irq is > wrong. First of all there's an off-by-one in the cleanup loop, which > can lead to unbinding wrong IRQs. > > Secondly IRQs not bound won't be freed, thus leaking IRQ numbers. > > Note that there's no need to differentiate between bound and unbound > IRQs when freeing them, __unbind_from_irq will deal with both of them > correctly. It appears to me that it is safe to call __unbind_from_irq() after xen_irq_info_common_setup() fails, but *not* if the latter hasn't been called at all. In that case the IRQ type will still be set to IRQT_UNBOUND and this will trigger the BUG_ON() in __unbind_from_irq(). [...] > --- a/drivers/xen/events/events_base.c > +++ b/drivers/xen/events/events_base.c > @@ -764,8 +764,8 @@ out: > mutex_unlock(&irq_mapping_update_lock); > return irq; > error_irq: > - for (; i >= 0; i--) > - __unbind_from_irq(irq + i); > + while (nvec--) > + __unbind_from_irq(irq + nvec); If nvec > 1, and xen_irq_info_pirq_setup() fails for i != nvec - 1, then we reach here without having called xen_irq_info_common_setup() for all these IRQs. In that case, I think we will still want to call xen_free_irq() for all IRQs. So maybe the fix would be to remove the BUG_ON() in __unbind_from_irq()? Ben. > mutex_unlock(&irq_mapping_update_lock); > return ret; > } -- Ben Hutchings, Software Developer Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom
