6.6-stable review patch. If anyone has any objections, please let me know.
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From: Amery Hung ameryhung@gmail.com
[ Upstream commit 87bcef158ac1faca1bd7e0104588e8e2956d10be ]
XDP programs can change the layout of an xdp_buff through bpf_xdp_adjust_tail() and bpf_xdp_adjust_head(). Therefore, the driver cannot assume the size of the linear data area nor fragments. Fix the bug in mlx5 by generating skb according to xdp_buff after XDP programs run.
Currently, when handling multi-buf XDP, the mlx5 driver assumes the layout of an xdp_buff to be unchanged. That is, the linear data area continues to be empty and fragments remain the same. This may cause the driver to generate erroneous skb or triggering a kernel warning. When an XDP program added linear data through bpf_xdp_adjust_head(), the linear data will be ignored as mlx5e_build_linear_skb() builds an skb without linear data and then pull data from fragments to fill the linear data area. When an XDP program has shrunk the non-linear data through bpf_xdp_adjust_tail(), the delta passed to __pskb_pull_tail() may exceed the actual nonlinear data size and trigger the BUG_ON in it.
To fix the issue, first record the original number of fragments. If the number of fragments changes after the XDP program runs, rewind the end fragment pointer by the difference and recalculate the truesize. Then, build the skb with the linear data area matching the xdp_buff. Finally, only pull data in if there is non-linear data and fill the linear part up to 256 bytes.
Fixes: f52ac7028bec ("net/mlx5e: RX, Add XDP multi-buffer support in Striding RQ") Signed-off-by: Amery Hung ameryhung@gmail.com Signed-off-by: Tariq Toukan tariqt@nvidia.com Link: https://patch.msgid.link/1760644540-899148-3-git-send-email-tariqt@nvidia.co... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- .../net/ethernet/mellanox/mlx5/core/en_rx.c | 26 ++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index 54268892148d4..fcf7437174e18 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -2024,6 +2024,7 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w u32 byte_cnt = cqe_bcnt; struct skb_shared_info *sinfo; unsigned int truesize = 0; + u32 pg_consumed_bytes; struct bpf_prog *prog; struct sk_buff *skb; u32 linear_frame_sz; @@ -2075,7 +2076,8 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w
while (byte_cnt) { /* Non-linear mode, hence non-XSK, which always uses PAGE_SIZE. */ - u32 pg_consumed_bytes = min_t(u32, PAGE_SIZE - frag_offset, byte_cnt); + pg_consumed_bytes = + min_t(u32, PAGE_SIZE - frag_offset, byte_cnt);
if (test_bit(MLX5E_RQ_STATE_SHAMPO, &rq->state)) truesize += pg_consumed_bytes; @@ -2091,10 +2093,15 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w }
if (prog) { + u8 nr_frags_free, old_nr_frags = sinfo->nr_frags; + u32 len; + if (mlx5e_xdp_handle(rq, prog, mxbuf)) { if (__test_and_clear_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags)) { struct mlx5e_frag_page *pfp;
+ frag_page -= old_nr_frags - sinfo->nr_frags; + for (pfp = head_page; pfp < frag_page; pfp++) pfp->frags++;
@@ -2104,9 +2111,19 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w return NULL; /* page/packet was consumed by XDP */ }
+ nr_frags_free = old_nr_frags - sinfo->nr_frags; + if (unlikely(nr_frags_free)) { + frag_page -= nr_frags_free; + truesize -= (nr_frags_free - 1) * PAGE_SIZE + + ALIGN(pg_consumed_bytes, + BIT(rq->mpwqe.log_stride_sz)); + } + + len = mxbuf->xdp.data_end - mxbuf->xdp.data; + skb = mlx5e_build_linear_skb( rq, mxbuf->xdp.data_hard_start, linear_frame_sz, - mxbuf->xdp.data - mxbuf->xdp.data_hard_start, 0, + mxbuf->xdp.data - mxbuf->xdp.data_hard_start, len, mxbuf->xdp.data - mxbuf->xdp.data_meta); if (unlikely(!skb)) { mlx5e_page_release_fragmented(rq, &wi->linear_page); @@ -2130,8 +2147,11 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w do pagep->frags++; while (++pagep < frag_page); + + headlen = min_t(u16, MLX5E_RX_MAX_HEAD - len, + skb->data_len); + __pskb_pull_tail(skb, headlen); } - __pskb_pull_tail(skb, headlen); } else { dma_addr_t addr;