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Commit f9f300a9 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Greg Kroah-Hartman
Browse files

ovl: fix warning in ovl_create_real() 



commit 1f5573cfe7a7056e80a92c7a037a3e69f3a13d1c upstream.

Syzbot triggered the following warning in ovl_workdir_create() ->
ovl_create_real():

	if (!err && WARN_ON(!newdentry->d_inode)) {

The reason is that the cgroup2 filesystem returns from mkdir without
instantiating the new dentry.

Weird filesystems such as this will be rejected by overlayfs at a later
stage during setup, but to prevent such a warning, call ovl_mkdir_real()
directly from ovl_workdir_create() and reject this case early.

Reported-and-tested-by: default avatar <syzbot+75eab84fd0af9e8bf66b@syzkaller.appspotmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ba2a9d8f

fs/overlayfs/dir.c

+1 −2
Original line number Diff line number Diff line
@@ -113,8 +113,7 @@ int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir, 
	goto out;

}



static int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry,

			  umode_t mode)

int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, umode_t mode)

{

	int err;

	struct dentry *d, *dentry = *newdentry;

fs/overlayfs/overlayfs.h

+1 −0
Original line number Diff line number Diff line
@@ -409,6 +409,7 @@ struct ovl_cattr { 


#define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })



int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, umode_t mode);

struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,

			       struct ovl_cattr *attr);

int ovl_cleanup(struct inode *dir, struct dentry *dentry);

fs/overlayfs/super.c

+8 −4
Original line number Diff line number Diff line
@@ -650,10 +650,14 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, 
			goto retry;

		}



		work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode));

		err = PTR_ERR(work);

		if (IS_ERR(work))

			goto out_err;

		err = ovl_mkdir_real(dir, &work, attr.ia_mode);

		if (err)

			goto out_dput;



		/* Weird filesystem returning with hashed negative (kernfs)? */

		err = -EINVAL;

		if (d_really_is_negative(work))

			goto out_dput;



		/*

		 * Try to remove POSIX ACL xattrs from workdir.  We are good if: