adm80211: add checks for dma mapping errors

The driver does not check if mapping dma memory succeed.
The patch adds the checks and failure handling.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/admtek/adm8211.c

@@ -413,6 +413,13 @@ static void adm8211_interrupt_rci(struct ieee80211_hw *dev)
 						       skb_tail_pointer(newskb),
 						       RX_PKT_SIZE,
 						       PCI_DMA_FROMDEVICE);
+				if (pci_dma_mapping_error(priv->pdev,
+					   priv->rx_buffers[entry].mapping)) {
+					priv->rx_buffers[entry].skb = NULL;
+					dev_kfree_skb(newskb);
+					skb = NULL;
+					/* TODO: update rx dropped stats */
+				}
 			} else {
 				skb = NULL;
 				/* TODO: update rx dropped stats */
@@ -1450,6 +1457,12 @@ static int adm8211_init_rings(struct ieee80211_hw *dev)
 						  skb_tail_pointer(rx_info->skb),
 						  RX_PKT_SIZE,
 						  PCI_DMA_FROMDEVICE);
+		if (pci_dma_mapping_error(priv->pdev, rx_info->mapping)) {
+			dev_kfree_skb(rx_info->skb);
+			rx_info->skb = NULL;
+			break;
+		}
+
 		desc->buffer1 = cpu_to_le32(rx_info->mapping);
 		desc->status = cpu_to_le32(RDES0_STATUS_OWN | RDES0_STATUS_SQL);
 	}
@@ -1613,7 +1626,7 @@ static void adm8211_calc_durations(int *dur, int *plcp, size_t payload_len, int
 }
 
 /* Transmit skb w/adm8211_tx_hdr (802.11 header created by hardware) */
-static void adm8211_tx_raw(struct ieee80211_hw *dev, struct sk_buff *skb,
+static int adm8211_tx_raw(struct ieee80211_hw *dev, struct sk_buff *skb,
 			   u16 plcp_signal,
 			   size_t hdrlen)
 {
@@ -1625,6 +1638,8 @@ static void adm8211_tx_raw(struct ieee80211_hw *dev, struct sk_buff *skb,
 
 	mapping = pci_map_single(priv->pdev, skb->data, skb->len,
 				 PCI_DMA_TODEVICE);
+	if (pci_dma_mapping_error(priv->pdev, mapping))
+		return -ENOMEM;
 
 	spin_lock_irqsave(&priv->lock, flags);
 
@@ -1657,6 +1672,8 @@ static void adm8211_tx_raw(struct ieee80211_hw *dev, struct sk_buff *skb,
 
 	/* Trigger transmit poll */
 	ADM8211_CSR_WRITE(TDR, 0);
+
+	return 0;
 }
 
 /* Put adm8211_tx_hdr on skb and transmit */
@@ -1710,7 +1727,10 @@ static void adm8211_tx(struct ieee80211_hw *dev,
 
 	txhdr->retry_limit = info->control.rates[0].count;
 
-	adm8211_tx_raw(dev, skb, plcp_signal, hdrlen);
+	if (adm8211_tx_raw(dev, skb, plcp_signal, hdrlen)) {
+		/* Drop packet */
+		ieee80211_free_txskb(dev, skb);
+	}
 }
 
 static int adm8211_alloc_rings(struct ieee80211_hw *dev)