From: Michael S. Tsirkin <mst@redhat.com>
Date: Thu, 14 Jan 2016 14:00:41 +0000 (+0200)
Subject: virtio_pci: fix use after free on release
X-Git-Tag: firefly_0821_release~176^2~475^2~250
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d56842d88978f54a3f7b8dfac3ae99ec3e732b95;p=firefly-linux-kernel-4.4.55.git

virtio_pci: fix use after free on release

commit 2989be09a8a9d62a785137586ad941f916e08f83 upstream.

KASan detected a use-after-free error in virtio-pci remove code. In
virtio_pci_remove(), vp_dev is still used after being freed in
unregister_virtio_device() (in virtio_pci_release_dev() more
precisely).

To fix, keep a reference until cleanup is done.

Fixes: 63bd62a08ca4 ("virtio_pci: defer kfree until release callback")
Reported-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 78f804af6c20..2046a68ad0ba 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -545,6 +545,7 @@ err_enable_device:
 static void virtio_pci_remove(struct pci_dev *pci_dev)
 {
 	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+	struct device *dev = get_device(&vp_dev->vdev.dev);
 
 	unregister_virtio_device(&vp_dev->vdev);
 
@@ -554,6 +555,7 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
 		virtio_pci_modern_remove(vp_dev);
 
 	pci_disable_device(pci_dev);
+	put_device(dev);
 }
 
 static struct pci_driver virtio_pci_driver = {