On Mon, Jul 27, 2020 at 03:43:28PM +0800, Jason Wang wrote:
> We try to get config from peer unconditionally which may lead NULL
> pointer dereference. Add a check before trying to access the config.
>
> Fixes: 108a64818e69b ("vhost-vdpa: introduce vhost-vdpa backend")
> Cc: Cindy Lu <[email protected]>
> Tested-by: Cornelia Huck <[email protected]>
> Signed-off-by: Jason Wang <[email protected]>
I am a bit lost here. Isn't this invoked
when guest attempts to read the config?
With no peer, what do we return to guest?
A code comment might be helpful here.
> ---
> hw/net/virtio-net.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 4895af1cbe..935b9ef5c7 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -125,6 +125,7 @@ static void virtio_net_get_config(VirtIODevice *vdev,
> uint8_t *config)
> {
> VirtIONet *n = VIRTIO_NET(vdev);
> struct virtio_net_config netcfg;
> + NetClientState *nc = qemu_get_queue(n->nic);
>
> int ret = 0;
> memset(&netcfg, 0 , sizeof(struct virtio_net_config));
> @@ -142,13 +143,12 @@ static void virtio_net_get_config(VirtIODevice *vdev,
> uint8_t *config)
> VIRTIO_NET_RSS_SUPPORTED_HASHES);
> memcpy(config, &netcfg, n->config_size);
>
> - NetClientState *nc = qemu_get_queue(n->nic);
> - if (nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
> + if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
> ret = vhost_net_get_config(get_vhost_net(nc->peer), (uint8_t
> *)&netcfg,
> - n->config_size);
> - if (ret != -1) {
> - memcpy(config, &netcfg, n->config_size);
> - }
> + n->config_size);
> + if (ret != -1) {
> + memcpy(config, &netcfg, n->config_size);
> + }
> }
> }
>
> @@ -156,6 +156,7 @@ static void virtio_net_set_config(VirtIODevice *vdev,
> const uint8_t *config)
> {
> VirtIONet *n = VIRTIO_NET(vdev);
> struct virtio_net_config netcfg = {};
> + NetClientState *nc = qemu_get_queue(n->nic);
>
> memcpy(&netcfg, config, n->config_size);
>
> @@ -166,11 +167,10 @@ static void virtio_net_set_config(VirtIODevice *vdev,
> const uint8_t *config)
> qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
> }
>
> - NetClientState *nc = qemu_get_queue(n->nic);
> - if (nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
> - vhost_net_set_config(get_vhost_net(nc->peer), (uint8_t *)&netcfg,
> - 0, n->config_size,
> - VHOST_SET_CONFIG_TYPE_MASTER);
> + if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
> + vhost_net_set_config(get_vhost_net(nc->peer),
> + (uint8_t *)&netcfg, 0, n->config_size,
> + VHOST_SET_CONFIG_TYPE_MASTER);
> }
> }
>
> --
> 2.20.1
