From 74dd7c97ea2ab08b41925ab2f472db573accda89 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 9 Oct 2018 23:32:41 -0400
Subject: [Backport 74dd7c97ea2a] ecryptfs_rename(): verify that lower dentries
 are still OK after lock_rename()

We get lower layer dentries, find their parents, do lock_rename() and
proceed to vfs_rename().  However, we do not check that dentries still
have the same parents and are not unlinked.  Need to check that...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 src/inode.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/inode.c b/src/inode.c
index 49121e5a8de228acfb1ea126250e5ad94e4ec812..5c36ceecb5c12828ceb84a39d19c86b69713b937 100644
--- a/src/inode.c
+++ b/src/inode.c
@@ -593,11 +593,16 @@ ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	lower_new_dir_dentry = dget_parent(lower_new_dentry);
 	target_inode = d_inode(new_dentry);
 	trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+	rc = -EINVAL;
+	if (lower_old_dentry->d_parent != lower_old_dir_dentry)
+		goto out_lock;
+	if (lower_new_dentry->d_parent != lower_new_dir_dentry)
+		goto out_lock;
+	if (d_unhashed(lower_old_dentry) || d_unhashed(lower_new_dentry))
+		goto out_lock;
 	/* source should not be ancestor of target */
-	if (trap == lower_old_dentry) {
-		rc = -EINVAL;
+	if (trap == lower_old_dentry)
 		goto out_lock;
-	}
 	/* target should not be ancestor of source */
 	if (trap == lower_new_dentry) {
 		rc = -ENOTEMPTY;
-- 
2.31.1