netdev - Re: [PATCH net-next] mlx5: fix xdp data_meta setup in mlx5e_fill_xdp

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Message-ID: <41538e35-cc81-73b5-a63d-42a7176c1e74@gmail.com>
Date:   Wed, 27 May 2020 08:08:22 -0600
From:   David Ahern <dsahern@...il.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
        Björn Töpel <bjorn.topel@...el.com>
Cc:     Saeed Mahameed <saeedm@...lanox.com>
Subject: Re: [PATCH net-next] mlx5: fix xdp data_meta setup in
 mlx5e_fill_xdp_buff

On 5/27/20 7:44 AM, Jesper Dangaard Brouer wrote:
> The helper function xdp_set_data_meta_invalid() must be called after
> setting xdp->data as it depends on it.
> 
> The bug was introduced in 39d6443c8daf ("mlx5, xsk: Migrate to
> new MEM_TYPE_XSK_BUFF_POOL"), and cause the kernel to crash when
> using BPF helper bpf_xdp_adjust_head() on mlx5 driver.
> 
> Fixes: 39d6443c8daf ("mlx5, xsk: Migrate to new MEM_TYPE_XSK_BUFF_POOL")
> Reported-by: David Ahern <dsahern@...nel.org>
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_rx.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> index 6b3c82da199c..dbb1c6323967 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
> @@ -1056,8 +1056,8 @@ static void mlx5e_fill_xdp_buff(struct mlx5e_rq *rq, void *va, u16 headroom,
>  				u32 len, struct xdp_buff *xdp)
>  {
>  	xdp->data_hard_start = va;
> -	xdp_set_data_meta_invalid(xdp);
>  	xdp->data = va + headroom;
> +	xdp_set_data_meta_invalid(xdp);
>  	xdp->data_end = xdp->data + len;
>  	xdp->rxq = &rq->xdp_rxq;
>  	xdp->frame_sz = rq->buff.frame0_sz;
> 
> 

good catch. I looked right past that yesterday.

Tested-by: David Ahern <dsahern@...il.com>