virtio-pci: fix use after free

commit 72103bd1285211440621f2c46f4fce377584de54 upstream.

Commit 31a3ddda166cda86d2b5111e09ba4bda5239fae6 introduced
a use after free in virtio-pci. The main issue is
that the release method signals removal of the virtio device,
while remove signals removal of the pci device.

For example, on driver removal or hot-unplug,
virtio_pci_release_dev is called before virtio_pci_remove.
We then might get a crash as virtio_pci_remove tries to use the
device freed by virtio_pci_release_dev.

We allocate/free all resources together with the
pci device, so we can leave the release method empty.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 4bcc8b82640be13af193478aaa2c4699bc609d2b..ecb925411e09f85031692c0e71f6fbbab349653f 100644 (file)
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -590,11 +590,11 @@ 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_pci_device *vp_dev = to_vp_device(dev);
-
-       kfree(vp_dev);
+       /*
+        * No need for a release method as we allocate/free
+        * all devices together with the pci devices.
+        * Provide an empty one to avoid getting a warning from core.
+        */
 }
 
 /* the PCI probing function */
@@ -682,6 +682,7 @@ static void __devexit virtio_pci_remove(struct pci_dev *pci_dev)
        pci_iounmap(pci_dev, vp_dev->ioaddr);
        pci_release_regions(pci_dev);
        pci_disable_device(pci_dev);
+       kfree(vp_dev);
 }
 
 #ifdef CONFIG_PM