From 3bc41d6d2721d5168a8f7fea34028a5332068f5e Mon Sep 17 00:00:00 2001 From: Sven Van Asbroeck Date: Thu, 8 Apr 2021 20:39:04 -0400 Subject: lan743x: fix ethernet frame cutoff issue The ethernet frame length is calculated incorrectly. Depending on the value of RX_HEAD_PADDING, this may result in ethernet frames that are too short (cut off at the end), or too long (garbage added to the end). Fix by calculating the ethernet frame length correctly. For added clarity, use the ETH_FCS_LEN constant in the calculation. Many thanks to Heiner Kallweit for suggesting this solution. Suggested-by: Heiner Kallweit Fixes: 3e21a10fdea3 ("lan743x: trim all 4 bytes of the FCS; not just 2") Link: https://lore.kernel.org/lkml/20210408172353.21143-1-TheSven73@gmail.com/ Signed-off-by: Sven Van Asbroeck Reviewed-by: George McCollister Tested-by: George McCollister Link: https://lore.kernel.org/r/20210409003904.8957-1-TheSven73@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/microchip/lan743x_main.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/net/ethernet/microchip/lan743x_main.c') diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c index 1c3e204d727c..7b6794aa8ea9 100644 --- a/drivers/net/ethernet/microchip/lan743x_main.c +++ b/drivers/net/ethernet/microchip/lan743x_main.c @@ -885,8 +885,8 @@ static int lan743x_mac_set_mtu(struct lan743x_adapter *adapter, int new_mtu) } mac_rx &= ~(MAC_RX_MAX_SIZE_MASK_); - mac_rx |= (((new_mtu + ETH_HLEN + 4) << MAC_RX_MAX_SIZE_SHIFT_) & - MAC_RX_MAX_SIZE_MASK_); + mac_rx |= (((new_mtu + ETH_HLEN + ETH_FCS_LEN) + << MAC_RX_MAX_SIZE_SHIFT_) & MAC_RX_MAX_SIZE_MASK_); lan743x_csr_write(adapter, MAC_RX, mac_rx); if (enabled) { @@ -1944,7 +1944,7 @@ static int lan743x_rx_init_ring_element(struct lan743x_rx *rx, int index) struct sk_buff *skb; dma_addr_t dma_ptr; - buffer_length = netdev->mtu + ETH_HLEN + 4 + RX_HEAD_PADDING; + buffer_length = netdev->mtu + ETH_HLEN + ETH_FCS_LEN + RX_HEAD_PADDING; descriptor = &rx->ring_cpu_ptr[index]; buffer_info = &rx->buffer_info[index]; @@ -2040,7 +2040,7 @@ lan743x_rx_trim_skb(struct sk_buff *skb, int frame_length) dev_kfree_skb_irq(skb); return NULL; } - frame_length = max_t(int, 0, frame_length - RX_HEAD_PADDING - 4); + frame_length = max_t(int, 0, frame_length - ETH_FCS_LEN); if (skb->len > frame_length) { skb->tail -= skb->len - frame_length; skb->len = frame_length; -- cgit v1.2.3-59-g8ed1b