Merge tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull rename updates from Al Viro:
 "Fix directory locking scheme on rename

  This was broken in 6.5; we really can't lock two unrelated directories
  without holding ->s_vfs_rename_mutex first and in case of same-parent
  rename of a subdirectory 6.5 ends up doing just that"

* tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  rename(): avoid a deadlock in the case of parents having no common ancestor
  kill lock_two_inodes()
  rename(): fix the locking of subdirectories
  f2fs: Avoid reading renamed directory if parent does not change
  ext4: don't access the source subdirectory content on same-directory rename
  ext2: Avoid reading renamed directory if parent does not change
  udf_rename(): only access the child content on cross-directory rename
  ocfs2: Avoid touching renamed directory if parent does not change
  reiserfs: Avoid touching renamed directory if parent does not change

4 files changed, 20 insertions, 6 deletions

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 696478f09cc1..b8e25ca51016 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -744,7 +744,7 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 	struct inode *inode;
 	struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir);
 	struct path path = { .mnt = ovl_upper_mnt(ofs) };
-	struct dentry *temp, *upper;
+	struct dentry *temp, *upper, *trap;
 	struct ovl_cu_creds cc;
 	int err;
 	struct ovl_cattr cattr = {
@@ -781,11 +781,13 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 	 * temp wasn't moved before copy up completion or cleanup.
 	 */
 	ovl_start_write(c->dentry);
-	if (lock_rename(c->workdir, c->destdir) != NULL ||
-	    temp->d_parent != c->workdir) {
+	trap = lock_rename(c->workdir, c->destdir);
+	if (trap || temp->d_parent != c->workdir) {
 		/* temp or workdir moved underneath us? abort without cleanup */
 		dput(temp);
 		err = -EIO;
+		if (IS_ERR(trap))
+			goto out;
 		goto unlock;
 	} else if (err) {
 		goto cleanup;
@@ -826,6 +828,7 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 		ovl_set_flag(OVL_WHITEOUTS, inode);
 unlock:
 	unlock_rename(c->workdir, c->destdir);
+out:
 	ovl_end_write(c->dentry);
 
 	return err;
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index aab3f5d93556..0f8b4a719237 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -1180,6 +1180,10 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 	}
 
 	trap = lock_rename(new_upperdir, old_upperdir);
+	if (IS_ERR(trap)) {
+		err = PTR_ERR(trap);
+		goto out_revert_creds;
+	}
 
 	olddentry = ovl_lookup_upper(ofs, old->d_name.name, old_upperdir,
 				     old->d_name.len);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 0bbbe4818f67..4ab66e3d4cff 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -439,8 +439,10 @@ static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
 	bool ok = false;
 
 	if (workdir != upperdir) {
-		ok = (lock_rename(workdir, upperdir) == NULL);
-		unlock_rename(workdir, upperdir);
+		struct dentry *trap = lock_rename(workdir, upperdir);
+		if (!IS_ERR(trap))
+			unlock_rename(workdir, upperdir);
+		ok = (trap == NULL);
 	}
 	return ok;
 }
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 22b519763267..0217094c23ea 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -1198,12 +1198,17 @@ void ovl_nlink_end(struct dentry *dentry)
 
 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
 {
+	struct dentry *trap;
+
 	/* Workdir should not be the same as upperdir */
 	if (workdir == upperdir)
 		goto err;
 
 	/* Workdir should not be subdir of upperdir and vice versa */
-	if (lock_rename(workdir, upperdir) != NULL)
+	trap = lock_rename(workdir, upperdir);
+	if (IS_ERR(trap))
+		goto err;
+	if (trap)
 		goto err_unlock;
 
 	return 0;