ipw2x00: add checks for dma mapping errors

ipw2100_alloc_skb() and ipw2100_tx_send_data() do 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 <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>

drivers/net/wireless/intel/ipw2x00/ipw2100.c

···
 	packet->dma_addr = pci_map_single(priv->pci_dev, packet->skb->data,
 					  sizeof(struct ipw2100_rx),
 					  PCI_DMA_FROMDEVICE);
-	/* NOTE: pci_map_single does not return an error code, and 0 is a valid
-	 *       dma_addr */
+	if (pci_dma_mapping_error(priv->pci_dev, packet->dma_addr)) {
+		dev_kfree_skb(packet->skb);
+		return -ENOMEM;
+	}
 
 	return 0;
 }
···
 							LIBIPW_3ADDR_LEN,
 							tbd->buf_length,
 							PCI_DMA_TODEVICE);
+			if (pci_dma_mapping_error(priv->pci_dev,
+						  tbd->host_addr)) {
+				IPW_DEBUG_TX("dma mapping error\n");
+				break;
+			}
 
 			IPW_DEBUG_TX("data frag tbd TX%d P=%08x L=%d\n",
 				     txq->next, tbd->host_addr,