Re: [PATCH] virtio_pci: fix use after free on release

[Jerome Marchand]

On 01/14/2016 03:04 PM, Michael S. Tsirkin wrote:
> 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.

That does make KASan happy.

> 
> Fixes: 63bd62a08ca4 ("virtio_pci: defer kfree until release callback")
> Reported-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

Tested-by: Jerome Marchand <jmarchan@xxxxxxxxxx>

Thanks,
Jerome

> ---
>  drivers/virtio/virtio_pci_common.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index 36205c2..f6bed86 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 = {
>

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