virtio_pci: Prevent double-free of pci regions after device hot-unplug

In the case where a virtio-console port is in use (opened by a program)
and a virtio-console device is removed, the port is kept around but all
the virtio-related state is assumed to be gone.

When the port is finally released (close() called), we call
device_destroy() on the port's device.  This results in the parent
device's structures to be freed as well.  This includes the PCI regions
for the virtio-console PCI device.

Once this is done, however, virtio_pci_release_dev() kicks in, as the
last ref to the virtio device is now gone, and attempts to do

     pci_iounmap(pci_dev, vp_dev->ioaddr);
     pci_release_regions(pci_dev);
     pci_disable_device(pci_dev);

which results in a double-free warning.

Move the code that releases regions, etc., to the virtio_pci_remove()
function, and all that's now left in release_dev is the final freeing of
the vp_dev.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 4fb5b2bf2348..4bcc8b82640b 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -590,15 +590,10 @@ static struct virtio_config_ops virtio_pci_config_ops = {
 
 static void virtio_pci_release_dev(struct device *_d)
 {
-        struct virtio_device *dev = container_of(_d, struct virtio_device, dev);
+        struct virtio_device *dev = container_of(_d, struct virtio_device,
+                                                 dev);
         struct virtio_pci_device *vp_dev = to_vp_device(dev);
-        struct pci_dev *pci_dev = vp_dev->pci_dev;
 
-        vp_del_vqs(dev);
-        pci_set_drvdata(pci_dev, NULL);
-        pci_iounmap(pci_dev, vp_dev->ioaddr);
-        pci_release_regions(pci_dev);
-        pci_disable_device(pci_dev);
         kfree(vp_dev);
 }
 
@@ -681,6 +676,12 @@ static void __devexit virtio_pci_remove(struct pci_dev *pci_dev)
         struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
 
         unregister_virtio_device(&vp_dev->vdev);
+
+        vp_del_vqs(&vp_dev->vdev);
+        pci_set_drvdata(pci_dev, NULL);
+        pci_iounmap(pci_dev, vp_dev->ioaddr);
+        pci_release_regions(pci_dev);
+        pci_disable_device(pci_dev);
 }
 
 #ifdef CONFIG_PM