[PATCH 3.13 133/140] virtio-scsi: Fix hotcpu_notifier use-after-free with virtscsi_freeze

[Greg Kroah-Hartman]

3.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Asias He <asias.hejun@xxxxxxxxx>

commit f466f75385369a181409e46da272db3de6f5c5cb upstream.

vqs are freed in virtscsi_freeze but the hotcpu_notifier is not
unregistered. We will have a use-after-free usage when the notifier
callback is called after virtscsi_freeze.

Fixes: 285e71ea6f3583a85e27cb2b9a7d8c35d4c0d558
("virtio-scsi: reset virtqueue affinity when doing cpu hotplug")

Signed-off-by: Asias He <asias.hejun@xxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/scsi/virtio_scsi.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -956,6 +956,10 @@ static void virtscsi_remove(struct virti
 #ifdef CONFIG_PM_SLEEP
 static int virtscsi_freeze(struct virtio_device *vdev)
 {
+	struct Scsi_Host *sh = virtio_scsi_host(vdev);
+	struct virtio_scsi *vscsi = shost_priv(sh);
+
+	unregister_hotcpu_notifier(&vscsi->nb);
 	virtscsi_remove_vqs(vdev);
 	return 0;
 }
@@ -964,8 +968,17 @@ static int virtscsi_restore(struct virti
 {
 	struct Scsi_Host *sh = virtio_scsi_host(vdev);
 	struct virtio_scsi *vscsi = shost_priv(sh);
+	int err;
+
+	err = virtscsi_init(vdev, vscsi);
+	if (err)
+		return err;
+
+	err = register_hotcpu_notifier(&vscsi->nb);
+	if (err)
+		vdev->config->del_vqs(vdev);
 
-	return virtscsi_init(vdev, vscsi);
+	return err;
 }
 #endif
 


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