Re: [PATCH v2 2/2] ebpf: Fix indirections table setting

[Yuri Benditovich]

Hi Andrew,
Can you please check the indirection table copy and ack on the patch
if the fix is correct

Thanks,
Yuri

On Wed, Mar 27, 2024 at 4:05 AM Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
>
> The kernel documentation says:
> > The value stored can be of any size, however, all array elements are
> > aligned to 8 bytes.
> https://www.kernel.org/doc/html/v6.8/bpf/map_array.html
>
> Fixes: 333b3e5fab75 ("ebpf: Added eBPF map update through mmap.")
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>  ebpf/ebpf_rss.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/ebpf/ebpf_rss.c b/ebpf/ebpf_rss.c
> index 2e506f974357..d102f3dd0929 100644
> --- a/ebpf/ebpf_rss.c
> +++ b/ebpf/ebpf_rss.c
> @@ -185,13 +185,18 @@ static bool ebpf_rss_set_indirections_table(struct 
> EBPFRSSContext *ctx,
>                                              uint16_t *indirections_table,
>                                              size_t len)
>  {
> +    char *cursor = ctx->mmap_indirections_table;
> +
>      if (!ebpf_rss_is_loaded(ctx) || indirections_table == NULL ||
>         len > VIRTIO_NET_RSS_MAX_TABLE_LEN) {
>          return false;
>      }
>
> -    memcpy(ctx->mmap_indirections_table, indirections_table,
> -            sizeof(*indirections_table) * len);
> +    for (size_t i = 0; i < len; i++) {
> +        *(uint16_t *)cursor = indirections_table[i];
> +        cursor += 8;
> +    }
> +
>      return true;
>  }
>
>
> --
> 2.44.0
>