From 180012dc05e565260a25696767c8f5b2df5fc50e Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Sat, 16 Apr 2016 11:25:53 +0100 Subject: [PATCH] nfp: remove buggy RX buffer length validation Meaning of data_len and meta_len RX WB descriptor fields is slightly confusing. Add a comment with a diagram clarifying the layout. Also remove the buffer length validation: (a) it's imprecise for static rx-offsets; (b) if firmware is buggy enough to DMA past the end of the buffer WARN_ON_ONCE() doesn't seem like a strong enough response. skb_put() will do the checking for us anyway. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller --- .../ethernet/netronome/nfp/nfp_net_common.c | 26 ++++++++++--------- 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c index 0bdff390c958..5235e86eb684 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c @@ -1298,23 +1298,25 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, int budget) nfp_net_rx_give_one(rx_ring, new_skb, new_dma_addr); + /* < meta_len > + * <-- [rx_offset] --> + * --------------------------------------------------------- + * | [XX] | metadata | packet | XXXX | + * --------------------------------------------------------- + * <---------------- data_len ---------------> + * + * The rx_offset is fixed for all packets, the meta_len can vary + * on a packet by packet basis. If rx_offset is set to zero + * (_RX_OFFSET_DYNAMIC) metadata starts at the beginning of the + * buffer and is immediately followed by the packet (no [XX]). + */ meta_len = rxd->rxd.meta_len_dd & PCIE_DESC_RX_META_LEN_MASK; data_len = le16_to_cpu(rxd->rxd.data_len); - if (WARN_ON_ONCE(data_len > nn->fl_bufsz)) { - dev_kfree_skb_any(skb); - continue; - } - - if (nn->rx_offset == NFP_NET_CFG_RX_OFFSET_DYNAMIC) { - /* The packet data starts after the metadata */ + if (nn->rx_offset == NFP_NET_CFG_RX_OFFSET_DYNAMIC) skb_reserve(skb, meta_len); - } else { - /* The packet data starts at a fixed offset */ + else skb_reserve(skb, nn->rx_offset); - } - - /* Adjust the SKB for the dynamic meta data pre-pended */ skb_put(skb, data_len - meta_len); nfp_net_set_hash(nn->netdev, skb, rxd); -- 2.34.1