On Mon, Nov 04, 2024 at 04:57:03PM +0800, Philo Lu wrote:
> When reading/writing virtio_net_ctrl_rss, we get the indirection table
> size from vi->rss_indir_table_size, which is initialized in
> virtnet_probe(). However, the actual size of indirection_table was set
> as VIRTIO_NET_RSS_MAX_TABLE_LEN=128. This collision may cause issues if
> the vi->rss_indir_table_size exceeds 128.
>
> This patch instead uses dynamic indirection table, allocated with
> vi->rss after vi->rss_indir_table_size initialized. And free it in
> virtnet_remove().
>
> In virtnet_commit_rss_command(), sgs for rss is initialized differently
> with hash_report. So indirection_table is not used if !vi->has_rss, and
> then we don't need to alloc indirection_table for hash_report only uses.
>
> Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.")
> Signed-off-by: Philo Lu <lu...@linux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
> ---
> drivers/net/virtio_net.c | 39 ++++++++++++++++++++++++++++++++++-----
> 1 file changed, 34 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 869586c17ffd..75c1ff4efd13 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -368,15 +368,16 @@ struct receive_queue {
> * because table sizes may be differ according to the device configuration.
> */
> #define VIRTIO_NET_RSS_MAX_KEY_SIZE 40
> -#define VIRTIO_NET_RSS_MAX_TABLE_LEN 128
> struct virtio_net_ctrl_rss {
> u32 hash_types;
> u16 indirection_table_mask;
> u16 unclassified_queue;
> - u16 indirection_table[VIRTIO_NET_RSS_MAX_TABLE_LEN];
> + u16 hash_cfg_reserved; /* for HASH_CONFIG (see virtio_net_hash_config
> for details) */
> u16 max_tx_vq;
> u8 hash_key_length;
> u8 key[VIRTIO_NET_RSS_MAX_KEY_SIZE];
> +
> + u16 *indirection_table;
> };
>
> /* Control VQ buffers: protected by the rtnl lock */
> @@ -512,6 +513,25 @@ static struct sk_buff *virtnet_skb_append_frag(struct
> sk_buff *head_skb,
> struct page *page, void *buf,
> int len, int truesize);
>
> +static int rss_indirection_table_alloc(struct virtio_net_ctrl_rss *rss, u16
> indir_table_size)
> +{
> + if (!indir_table_size) {
> + rss->indirection_table = NULL;
> + return 0;
> + }
> +
> + rss->indirection_table = kmalloc_array(indir_table_size, sizeof(u16),
> GFP_KERNEL);
> + if (!rss->indirection_table)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +static void rss_indirection_table_free(struct virtio_net_ctrl_rss *rss)
> +{
> + kfree(rss->indirection_table);
> +}
> +
> static bool is_xdp_frame(void *ptr)
> {
> return (unsigned long)ptr & VIRTIO_XDP_FLAG;
> @@ -3828,11 +3848,15 @@ static bool virtnet_commit_rss_command(struct
> virtnet_info *vi)
> /* prepare sgs */
> sg_init_table(sgs, 4);
>
> - sg_buf_size = offsetof(struct virtio_net_ctrl_rss, indirection_table);
> + sg_buf_size = offsetof(struct virtio_net_ctrl_rss, hash_cfg_reserved);
> sg_set_buf(&sgs[0], &vi->rss, sg_buf_size);
>
> - sg_buf_size = sizeof(uint16_t) * (vi->rss.indirection_table_mask + 1);
> - sg_set_buf(&sgs[1], vi->rss.indirection_table, sg_buf_size);
> + if (vi->has_rss) {
> + sg_buf_size = sizeof(uint16_t) * vi->rss_indir_table_size;
> + sg_set_buf(&sgs[1], vi->rss.indirection_table, sg_buf_size);
> + } else {
> + sg_set_buf(&sgs[1], &vi->rss.hash_cfg_reserved,
> sizeof(uint16_t));
> + }
>
> sg_buf_size = offsetof(struct virtio_net_ctrl_rss, key)
> - offsetof(struct virtio_net_ctrl_rss, max_tx_vq);
> @@ -6420,6 +6444,9 @@ static int virtnet_probe(struct virtio_device *vdev)
> virtio_cread16(vdev, offsetof(struct virtio_net_config,
> rss_max_indirection_table_length));
> }
> + err = rss_indirection_table_alloc(&vi->rss, vi->rss_indir_table_size);
> + if (err)
> + goto free;
>
> if (vi->has_rss || vi->has_rss_hash_report) {
> vi->rss_key_size =
> @@ -6674,6 +6701,8 @@ static void virtnet_remove(struct virtio_device *vdev)
>
> remove_vq_common(vi);
>
> + rss_indirection_table_free(&vi->rss);
> +
> free_netdev(vi->dev);
> }
>
I'm not an expert on virtio, so I don't feel comfortable giving a
Reviewed-by, but this does seem to fix a potential out of bounds
access in virtnet_init_default_rss if rss_indir_table_size were
larger than VIRTIO_NET_RSS_MAX_TABLE_LEN (128).
Acked-by: Joe Damato <jdam...@fastly.com>
