xen/pirq: fix error path cleanup when binding MSIs

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.

Fixes: 4892c9b4ada9f9 ("xen: add support for MSI message groups")
Reported-by: Hooman Mirhadi <mirhadih@amazon.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Amit Shah <aams@amazon.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 1ab4bd11f5f3f01f34b1a0055f836c9a0ce755ba..762378f1811cc9069dc6171edb55aaa3610b82fa 100644 (file)
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -755,8 +755,8 @@ 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);
        mutex_unlock(&irq_mapping_update_lock);
        return ret;
 }