ecryptfs: don't ignore return value from lock_rename

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Cc: Dustin Kirkland <kirkland@canonical.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

fs/ecryptfs/inode.c

@@ -614,6 +614,7 @@ ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	struct dentry *lower_new_dentry;
 	struct dentry *lower_old_dir_dentry;
 	struct dentry *lower_new_dir_dentry;
+	struct dentry *trap = NULL;
 
 	lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
 	lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
@@ -621,7 +622,17 @@ ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	dget(lower_new_dentry);
 	lower_old_dir_dentry = dget_parent(lower_old_dentry);
 	lower_new_dir_dentry = dget_parent(lower_new_dentry);
-	lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+	trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+	/* source should not be ancestor of target */
+	if (trap == lower_old_dentry) {
+		rc = -EINVAL;
+		goto out_lock;
+	}
+	/* target should not be ancestor of source */
+	if (trap == lower_new_dentry) {
+		rc = -ENOTEMPTY;
+		goto out_lock;
+	}
 	rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
 			lower_new_dir_dentry->d_inode, lower_new_dentry);
 	if (rc)