mtd: Fix kernel NULL pointer dereference in physmap.c

During the probe for physmap platform flash devices there are a
number error exit conditions that all do a goto err_out which
then calls physmap_flash_remove().  In that function one of the
cleanup steps is:

#ifdef CONFIG_MTD_CONCAT
	if (info->cmtd != info->mtd[0])
		mtd_concat_destroy(info->cmtd);
#endif

This test will succeed since info->cmtd == NULL and info->mtd[0] is
valid.

Fix this by exiting the remove function when info->cmtd == NULL.

Also, cleanup the #ifdef CONFIG_MTD_PARTITIONS stuff by using
mtd_has_partitions().
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/maps/physmap.c

@@ -44,22 +44,23 @@ static int physmap_flash_remove(struct platform_device *dev)
 		return 0;
 	platform_set_drvdata(dev, NULL);
 
+	if (info->cmtd == NULL)
+		return 0;
+
 	physmap_data = dev->dev.platform_data;
 
-	if (info->cmtd) {
-#ifdef CONFIG_MTD_PARTITIONS
-		if (info->nr_parts || physmap_data->nr_parts)
+	if (mtd_has_partitions()) {
+		if (info->nr_parts || physmap_data->nr_parts) {
 			del_mtd_partitions(info->cmtd);
-		else
+
+			if (info->nr_parts)
+				kfree(info->parts);
+		} else {
 			del_mtd_device(info->cmtd);
-#else
+		}
+	} else {
 		del_mtd_device(info->cmtd);
-#endif
 	}
-#ifdef CONFIG_MTD_PARTITIONS
-	if (info->nr_parts)
-		kfree(info->parts);
-#endif
 
 #ifdef CONFIG_MTD_CONCAT
 	if (info->cmtd != info->mtd[0])
@@ -169,7 +170,7 @@ static int physmap_flash_probe(struct platform_device *dev)
 	if (err)
 		goto err_out;
 
-#ifdef CONFIG_MTD_PARTITIONS
+	if (mtd_has_partitions()) {
 		err = parse_mtd_partitions(info->cmtd, part_probe_types,
 					&info->parts, 0);
 		if (err > 0) {
@@ -184,7 +185,7 @@ static int physmap_flash_probe(struct platform_device *dev)
 					physmap_data->nr_parts);
 			return 0;
 		}
-#endif
+	}
 
 	add_mtd_device(info->cmtd);
 	return 0;