fs: ext4: Fix free(NULL)

The 'depth_dirname', 'ptr', 'parent_inode' and 'first_inode' pointers
may be null. Thus, it is necessary to check them before using free() to
avoid free(NULL) cases.

Fixes: 934b14f2bb30 ("ext4: free allocations by parse_path()")
Signed-off-by: Mikhail Ilin <ilin.mikhail.ol@gmail.com>
diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index 1185cb2..f50de7c 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -850,15 +850,20 @@
 
 fail:
 	free(depth_dirname);
-	free(parse_dirname);
-	for (i = 0; i < depth; i++) {
-		if (!ptr[i])
-			break;
-		free(ptr[i]);
+	if (parse_dirname)
+		free(parse_dirname);
+	if (ptr) {
+		for (i = 0; i < depth; i++) {
+			if (!ptr[i])
+				break;
+			free(ptr[i]);
+		}
+		free(ptr);
 	}
-	free(ptr);
-	free(parent_inode);
-	free(first_inode);
+	if (parent_inode)
+		free(parent_inode);
+	if (first_inode)
+		free(first_inode);
 
 	return result_inode_no;
 }