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Commit f73cc77c authored by Al Viro's avatar Al Viro Committed by Miklos Szeredi
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ovl: make ovl_create_real() cope with vfs_mkdir() safely 



vfs_mkdir() may succeed and leave the dentry passed to it unhashed and
negative.  ovl_create_real() is the last caller breaking when that
happens.

[amir: split re-factoring of ovl_create_temp() to prep patch
       add comment about unhashed dir after mkdir
       add pr_warn() if mkdir succeeds and lookup fails]

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 137ec526

fs/overlayfs/dir.c

+33 −1
Original line number Diff line number Diff line
@@ -114,6 +114,37 @@ 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 err;

	struct dentry *d, *dentry = *newdentry;



	err = ovl_do_mkdir(dir, dentry, mode);

	if (err)

		return err;



	if (likely(!d_unhashed(dentry)))

		return 0;



	/*

	 * vfs_mkdir() may succeed and leave the dentry passed

	 * to it unhashed and negative. If that happens, try to

	 * lookup a new hashed and positive dentry.

	 */

	d = lookup_one_len(dentry->d_name.name, dentry->d_parent,

			   dentry->d_name.len);

	if (IS_ERR(d)) {

		pr_warn("overlayfs: failed lookup after mkdir (%pd2, err=%i).\n",

			dentry, err);

		return PTR_ERR(d);

	}

	dput(dentry);

	*newdentry = d;



	return 0;

}



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

			       struct ovl_cattr *attr)

{
@@ -135,7 +166,8 @@ struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry, 
			break;



		case S_IFDIR:

			err = ovl_do_mkdir(dir, newdentry, attr->mode);

			/* mkdir is special... */

			err =  ovl_mkdir_real(dir, &newdentry, attr->mode);

			break;



		case S_IFCHR: