Linux Virtualization - Jan 2017 - [PATCH v2] virtio_console: fix a crash in config_work_handler

Using control_work instead of config_work as the 3rd argument to
container_of results in an invalid portdev pointer. Indeed, the work
structure is initialized as below:

    INIT_WORK(&portdev->config_work, &config_work_handler);

It leads to a crash when portdev->vdev is dereferenced later. This bug
is triggered when the guest uses a virtio-console without multiport
feature and receives a config_changed virtio interrupt.

Signed-off-by: G. Campana <gcampana at quarkslab.com>
---
 drivers/char/virtio_console.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 8b00e79..17857be 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1862,7 +1862,7 @@ static void config_work_handler(struct work_struct *work)
 {
 	struct ports_device *portdev;
 
-	portdev = container_of(work, struct ports_device, control_work);
+	portdev = container_of(work, struct ports_device, config_work);
 	if (!use_multiport(portdev)) {
 		struct virtio_device *vdev;
 		struct port *port;
-- 
2.7.4

On (Mon) 16 Jan 2017 [10:45:02], G. Campana wrote:
> Using control_work instead of config_work as the 3rd argument to
> container_of results in an invalid portdev pointer. Indeed, the work
> structure is initialized as below:
> 
>     INIT_WORK(&portdev->config_work, &config_work_handler);
> 
> It leads to a crash when portdev->vdev is dereferenced later. This bug
> is triggered when the guest uses a virtio-console without multiport
> feature and receives a config_changed virtio interrupt.
> 
> Signed-off-by: G. Campana <gcampana at quarkslab.com>
Reviewed-by: Amit Shah <amit.shah at redhat.com>

Michael, can you please pick this up?

		Amit

On Mon, Jan 16, 2017 at 03:57:23PM +0530, Amit Shah
wrote:
> On (Mon) 16 Jan 2017 [10:45:02], G. Campana wrote:
> > Using control_work instead of config_work as the 3rd argument to
> > container_of results in an invalid portdev pointer. Indeed, the work
> > structure is initialized as below:
> > 
> >     INIT_WORK(&portdev->config_work, &config_work_handler);
> > 
> > It leads to a crash when portdev->vdev is dereferenced later. This
bug
> > is triggered when the guest uses a virtio-console without multiport
> > feature and receives a config_changed virtio interrupt.
> > 
> > Signed-off-by: G. Campana <gcampana at quarkslab.com>
> 
> Reviewed-by: Amit Shah <amit.shah at redhat.com>
> 
> Michael, can you please pick this up?
> 
> 		Amit
Sure.