Re: [PATCH] vdpa net: zero vhost_vdpa iova_tree pointer at cleanup

[Si-Wei Liu]

On 9/13/2023 5:34 AM, Eugenio Pérez wrote:
> Not zeroing it causes a SIGSEGV if the live migration is cancelled, at
> net device restart.
>
> This is caused because CVQ tries to reuse the iova_tree that is present
> in the first vhost_vdpa device at the end of vhost_vdpa_net_cvq_start.
> As a consequence, it tries to access an iova_tree that has been already
> free.
>
> Fixes: 00ef422e9fbf ("vdpa net: move iova tree creation from init to start")
> Reported-by: Yanhui Ma <yama@redhat.com>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
> ---
>   net/vhost-vdpa.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 34202ca009..1714ff4b11 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -385,6 +385,8 @@ static void vhost_vdpa_net_client_stop(NetClientState *nc)
>       dev = s->vhost_vdpa.dev;
>       if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
>           g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
> +    } else {
> +        s->vhost_vdpa.iova_tree = NULL;
>       }
>   }
>