[PATCH 3/4] Add error check for pci_map_single return value in rtl8180 TX path

[andrea merello <andrea.merello@gmail.com>]

From: "andrea.merello" <andrea.merello@gmail.com>

Orignal code will not detect a DMA mapping failure, causing the HW
to attempt a DMA from an invalid address.

This patch add the error check and eventually simply drops the TX
packet if we can't map it for DMA.

Signed-off-by: andrea.merello <andrea.merello@gmail.com>
Signed-off-by: andrea merello <andrea.merello@gmail.com>
---
 drivers/net/wireless/rtl818x/rtl8180/dev.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/wireless/rtl818x/rtl8180/dev.c b/drivers/net/wireless/rtl818x/rtl8180/dev.c
index 1c6ac25..9645ed2 100644
--- a/drivers/net/wireless/rtl818x/rtl8180/dev.c
+++ b/drivers/net/wireless/rtl818x/rtl8180/dev.c
@@ -276,6 +276,13 @@ static void rtl8180_tx(struct ieee80211_hw *dev,
 	mapping = pci_map_single(priv->pdev, skb->data,
 				 skb->len, PCI_DMA_TODEVICE);
 
+	if (pci_dma_mapping_error(priv->pdev, mapping)) {
+		kfree_skb(skb);
+		dev_err(&priv->pdev->dev, "TX DMA mapping error\n");
+		return;
+
+	}
+
 	tx_flags = RTL818X_TX_DESC_FLAG_OWN | RTL818X_TX_DESC_FLAG_FS |
 		   RTL818X_TX_DESC_FLAG_LS |
 		   (ieee80211_get_tx_rate(dev, info)->hw_value << 24) |
-- 
1.8.3.2