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authorSven Van Asbroeck <thesven73@gmail.com>2021-04-08 20:39:04 -0400
committerJakub Kicinski <kuba@kernel.org>2021-04-09 12:49:38 -0700
commit3bc41d6d2721d5168a8f7fea34028a5332068f5e (patch)
tree49f60782ab19f86874a50804a9f7d07addba04fb
parent864db232dc7036aa2de19749c3d5be0143b24f8f (diff)
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 <hkallweit1@gmail.com> 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 <thesven73@gmail.com> Reviewed-by: George McCollister <george.mccollister@gmail.com> Tested-by: George McCollister <george.mccollister@gmail.com> Link: https://lore.kernel.org/r/20210409003904.8957-1-TheSven73@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
-rw-r--r--drivers/net/ethernet/microchip/lan743x_main.c8
1 files changed, 4 insertions, 4 deletions
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;