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

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Date:   Wed, 27 May 2020 15:44:09 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     netdev@...r.kernel.org,
        Björn Töpel <bjorn.topel@...el.com>
Cc:     Jesper Dangaard Brouer <brouer@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [PATCH net-next] mlx5: fix xdp data_meta setup in mlx5e_fill_xdp_buff

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;