mtd: physmap: fix NULL pointer dereference in error path

commit e480814f13 ("[MTD] [MAPS] physmap:
fix wrong free and del_mtd_{partition,device}") introduces a NULL pointer
dereference in physmap_flash_remove when called from the error path in
physmap_flash_probe (if map_probe failed).

Call del_mtd_{partition,device} only if info->cmtd was not NULL.

Reported-by: pHilipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/mtd/maps/physmap.c

@@ -46,16 +46,19 @@ static int physmap_flash_remove(struct platform_device *dev)
 
 	physmap_data = dev->dev.platform_data;
 
+	if (info->cmtd) {
 #ifdef CONFIG_MTD_PARTITIONS
-	if (info->nr_parts) {
-		del_mtd_partitions(info->cmtd);
-		kfree(info->parts);
-	} else if (physmap_data->nr_parts)
-		del_mtd_partitions(info->cmtd);
-	else
-		del_mtd_device(info->cmtd);
+		if (info->nr_parts || physmap_data->nr_parts)
+			del_mtd_partitions(info->cmtd);
+		else
+			del_mtd_device(info->cmtd);
 #else
-	del_mtd_device(info->cmtd);
+		del_mtd_device(info->cmtd);
+#endif
+	}
+#ifdef CONFIG_MTD_PARTITIONS
+	if (info->nr_parts)
+		kfree(info->parts);
 #endif
 
 #ifdef CONFIG_MTD_CONCAT