vfio: Move PCI INTx eventfd setting earlier

We need to be ready to recieve an interrupt as soon as we call
request_irq, so our eventfd context setting needs to be moved
earlier.  Without this, an interrupt from our device or one
sharing the interrupt line can pass a NULL into eventfd_signal
and oops.

Cc: stable@vger.kernel.org
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index d8dedc7d3910..c8139a598f84 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -400,19 +400,20 @@ static int vfio_intx_set_signal(struct vfio_pci_device *vdev, int fd)
                 return PTR_ERR(trigger);
         }
 
+        vdev->ctx[0].trigger = trigger;
+
         if (!vdev->pci_2_3)
                 irqflags = 0;
 
         ret = request_irq(pdev->irq, vfio_intx_handler,
                           irqflags, vdev->ctx[0].name, vdev);
         if (ret) {
+                vdev->ctx[0].trigger = NULL;
                 kfree(vdev->ctx[0].name);
                 eventfd_ctx_put(trigger);
                 return ret;
         }
 
-        vdev->ctx[0].trigger = trigger;
-
         /*
          * INTx disable will stick across the new irq setup,
          * disable_irq won't.