tty: ipwireless: fix missing checks for ioremap

ipw->attr_memory and ipw->common_memory are assigned with the
return value of ioremap. ioremap may fail, but no checks
are enforced. The fix inserts the checks to avoid potential
NULL pointer dereferences.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/ipwireless/main.c

@@ -114,6 +114,10 @@ static int ipwireless_probe(struct pcmcia_device *p_dev, void *priv_data)
 
 	ipw->common_memory = ioremap(p_dev->resource[2]->start,
 				resource_size(p_dev->resource[2]));
+	if (!ipw->common_memory) {
+		ret = -ENOMEM;
+		goto exit1;
+	}
 	if (!request_mem_region(p_dev->resource[2]->start,
 				resource_size(p_dev->resource[2]),
 				IPWIRELESS_PCCARD_NAME)) {
@@ -134,6 +138,10 @@ static int ipwireless_probe(struct pcmcia_device *p_dev, void *priv_data)
 
 	ipw->attr_memory = ioremap(p_dev->resource[3]->start,
 				resource_size(p_dev->resource[3]));
+	if (!ipw->attr_memory) {
+		ret = -ENOMEM;
+		goto exit3;
+	}
 	if (!request_mem_region(p_dev->resource[3]->start,
 				resource_size(p_dev->resource[3]),
 				IPWIRELESS_PCCARD_NAME)) {