vfio/pci: fix use of freed memory

hw/vfio/pci.c:308:29: warning: Use of memory after it is freed
        qemu_set_fd_handler(*pfd, NULL, NULL, vdev);
                            ^~~~

Reported-by: Clang Static Analyzer
Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>

hw/vfio/pci.c

@@ -257,7 +257,7 @@ static void vfio_intx_update(PCIDevice *pdev)
 static int vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
 {
     uint8_t pin = vfio_pci_read_config(&vdev->pdev, PCI_INTERRUPT_PIN, 1);
-    int ret, argsz;
+    int ret, argsz, retval = 0;
     struct vfio_irq_set *irq_set;
     int32_t *pfd;
     Error *err = NULL;
@@ -302,12 +302,12 @@ static int vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
     qemu_set_fd_handler(*pfd, vfio_intx_interrupt, NULL, vdev);
 
     ret = ioctl(vdev->vbasedev.fd, VFIO_DEVICE_SET_IRQS, irq_set);
-    g_free(irq_set);
     if (ret) {
         error_setg_errno(errp, -ret, "failed to setup INTx fd");
         qemu_set_fd_handler(*pfd, NULL, NULL, vdev);
         event_notifier_cleanup(&vdev->intx.interrupt);
-        return -errno;
+        retval = -errno;
+        goto cleanup;
     }
 
     vfio_intx_enable_kvm(vdev, &err);
@@ -319,7 +319,10 @@ static int vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
 
     trace_vfio_intx_enable(vdev->vbasedev.name);
 
-    return 0;
+cleanup:
+    g_free(irq_set);
+
+    return retval;
 }
 
 static void vfio_intx_disable(VFIOPCIDevice *vdev)