[PATCH 5.4 163/177] net: lantiq: fix memory corruption in RX ring

[Greg Kroah-Hartman]

From: Aleksander Jan Bajkowski <olek2@xxxxx>

[ Upstream commit c7718ee96dbc2f9c5fc3b578abdf296dd44b9c20 ]

In a situation where memory allocation or dma mapping fails, an
invalid address is programmed into the descriptor. This can lead
to memory corruption. If the memory allocation fails, DMA should
reuse the previous skb and mapping and drop the packet. This patch
also increments rx drop counter.

Fixes: fe1a56420cf2 ("net: lantiq: Add Lantiq / Intel VRX200 Ethernet driver ")
Signed-off-by: Aleksander Jan Bajkowski <olek2@xxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/lantiq_xrx200.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c
index 4e44a39267eb..6ece99e6b6dd 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -154,6 +154,7 @@ static int xrx200_close(struct net_device *net_dev)
 
 static int xrx200_alloc_skb(struct xrx200_chan *ch)
 {
+	dma_addr_t mapping;
 	int ret = 0;
 
 	ch->skb[ch->dma.desc] = netdev_alloc_skb_ip_align(ch->priv->net_dev,
@@ -163,16 +164,17 @@ static int xrx200_alloc_skb(struct xrx200_chan *ch)
 		goto skip;
 	}
 
-	ch->dma.desc_base[ch->dma.desc].addr = dma_map_single(ch->priv->dev,
-			ch->skb[ch->dma.desc]->data, XRX200_DMA_DATA_LEN,
-			DMA_FROM_DEVICE);
-	if (unlikely(dma_mapping_error(ch->priv->dev,
-				       ch->dma.desc_base[ch->dma.desc].addr))) {
+	mapping = dma_map_single(ch->priv->dev, ch->skb[ch->dma.desc]->data,
+				 XRX200_DMA_DATA_LEN, DMA_FROM_DEVICE);
+	if (unlikely(dma_mapping_error(ch->priv->dev, mapping))) {
 		dev_kfree_skb_any(ch->skb[ch->dma.desc]);
 		ret = -ENOMEM;
 		goto skip;
 	}
 
+	ch->dma.desc_base[ch->dma.desc].addr = mapping;
+	/* Make sure the address is written before we give it to HW */
+	wmb();
 skip:
 	ch->dma.desc_base[ch->dma.desc].ctl =
 		LTQ_DMA_OWN | LTQ_DMA_RX_OFFSET(NET_IP_ALIGN) |
@@ -196,6 +198,8 @@ static int xrx200_hw_receive(struct xrx200_chan *ch)
 	ch->dma.desc %= LTQ_DESC_NUM;
 
 	if (ret) {
+		ch->skb[ch->dma.desc] = skb;
+		net_dev->stats.rx_dropped++;
 		netdev_err(net_dev, "failed to allocate new rx buffer\n");
 		return ret;
 	}
-- 
2.30.2