Linux Virtualization - Oct 2013 - [PATCH] virtio-scsi: Fix hotcpu_notifier use-after-free with virtscsi_freeze

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.

Signed-off-by: Asias He <asias at redhat.com>
---
 drivers/scsi/virtio_scsi.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 74b88ef..b26f1a5 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -957,6 +957,10 @@ static void virtscsi_remove(struct virtio_device *vdev)
 #ifdef CONFIG_PM
 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;
 }
@@ -965,8 +969,17 @@ static int virtscsi_restore(struct virtio_device *vdev)
 {
 	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
 
-- 
1.8.3.1

Il 28/10/2013 09:01, Asias He ha scritto:
> 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.
> 
> Signed-off-by: Asias He <asias at redhat.com>
> ---
>  drivers/scsi/virtio_scsi.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 74b88ef..b26f1a5 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -957,6 +957,10 @@ static void virtscsi_remove(struct virtio_device
*vdev)
>  #ifdef CONFIG_PM
>  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;
>  }
> @@ -965,8 +969,17 @@ static int virtscsi_restore(struct virtio_device
*vdev)
>  {
>  	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
>  
> 
Reviewed-by: Paolo Bonzini <pbonzini at redhat.com>
Cc: stable at vger.kernel.org

On 10/28/2013 04:01 PM, Asias He wrote:
> 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.
>
> Signed-off-by: Asias He <asias at redhat.com>
> ---
>  drivers/scsi/virtio_scsi.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 74b88ef..b26f1a5 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -957,6 +957,10 @@ static void virtscsi_remove(struct virtio_device
*vdev)
>  #ifdef CONFIG_PM
>  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;
>  }
> @@ -965,8 +969,17 @@ static int virtscsi_restore(struct virtio_device
*vdev)
>  {
>  	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
>  
Acked-by: Jason Wang <jasowang at redhat.com>

On 10/28/2013 04:01 PM, Asias He wrote:
> 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.
> 
> Signed-off-by: Asias He <asias at redhat.com>
Reviewed-by: Wanlong Gao <gaowanlong at cn.fujitsu.com>

> ---
>  drivers/scsi/virtio_scsi.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 74b88ef..b26f1a5 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -957,6 +957,10 @@ static void virtscsi_remove(struct virtio_device
*vdev)
>  #ifdef CONFIG_PM
>  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;
>  }
> @@ -965,8 +969,17 @@ static int virtscsi_restore(struct virtio_device
*vdev)
>  {
>  	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
>  
>

On 10/28/2013 04:01 PM, Asias He wrote:
> 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.
>
> Signed-off-by: Asias He <asias at redhat.com>
> ---
>  drivers/scsi/virtio_scsi.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 74b88ef..b26f1a5 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -957,6 +957,10 @@ static void virtscsi_remove(struct virtio_device
*vdev)
>  #ifdef CONFIG_PM
>  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;
>  }
> @@ -965,8 +969,17 @@ static int virtscsi_restore(struct virtio_device
*vdev)
>  {
>  	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
>  
Ping. Rusty, could you please review and apply this patch?

Thanks

Jason Wang <jasowang at redhat.com> writes:
> On 10/28/2013 04:01 PM, Asias He wrote:
>> 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.
>>
>> Signed-off-by: Asias He <asias at redhat.com>
Please include a Fixes: line, especially if you want the CC: stable.

Thanks,
Rusty.

>> ---
>>  drivers/scsi/virtio_scsi.c | 15 ++++++++++++++-
>>  1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
>> index 74b88ef..b26f1a5 100644
>> --- a/drivers/scsi/virtio_scsi.c
>> +++ b/drivers/scsi/virtio_scsi.c
>> @@ -957,6 +957,10 @@ static void virtscsi_remove(struct virtio_device
*vdev)
>>  #ifdef CONFIG_PM
>>  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;
>>  }
>> @@ -965,8 +969,17 @@ static int virtscsi_restore(struct virtio_device
*vdev)
>>  {
>>  	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
>>  
>
> Ping. Rusty, could you please review and apply this patch?
>
> Thanks