Commit be34d1a3 authored by David Howells's avatar David Howells Committed by Al Viro
Browse files

VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors 



copy_tree() can theoretically fail in a case other than ENOMEM, but always
returns NULL which is interpreted by callers as -ENOMEM.  Change it to return
an explicit error.

Also change clone_mnt() for consistency and because union mounts will add new
error cases.

Thanks to Andreas Gruenbacher <agruen@suse.de> for a bug fix.
[AV: folded braino fix by Dan Carpenter]

Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Cc: Valerie Aurora <valerie.aurora@gmail.com>
Cc: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 55e4def0

fs/namespace.c

+65 −55
Original line number Diff line number Diff line
@@ -708,16 +708,20 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, 
					int flag)

{

	struct super_block *sb = old->mnt.mnt_sb;

	struct mount *mnt = alloc_vfsmnt(old->mnt_devname);

	struct mount *mnt;

	int err;



	mnt = alloc_vfsmnt(old->mnt_devname);

	if (!mnt)

		return ERR_PTR(-ENOMEM);



	if (mnt) {

	if (flag & (CL_SLAVE | CL_PRIVATE))

		mnt->mnt_group_id = 0; /* not a peer of original */

	else

		mnt->mnt_group_id = old->mnt_group_id;



	if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {

			int err = mnt_alloc_group_id(mnt);

		err = mnt_alloc_group_id(mnt);

		if (err)

			goto out_free;

	}
@@ -752,12 +756,12 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, 
		if (!list_empty(&old->mnt_expire))

			list_add(&mnt->mnt_expire, &old->mnt_expire);

	}

	}



	return mnt;



 out_free:

	free_vfsmnt(mnt);

	return NULL;

	return ERR_PTR(err);

}



static inline void mntfree(struct mount *mnt)
@@ -1242,11 +1246,12 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, 
	struct path path;



	if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))

		return NULL;

		return ERR_PTR(-EINVAL);



	res = q = clone_mnt(mnt, dentry, flag);

	if (!q)

		goto Enomem;

	if (IS_ERR(q))

		return q;



	q->mnt_mountpoint = mnt->mnt_mountpoint;



	p = mnt;
@@ -1268,8 +1273,8 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, 
			path.mnt = &q->mnt;

			path.dentry = p->mnt_mountpoint;

			q = clone_mnt(p, p->mnt.mnt_root, flag);

			if (!q)

				goto Enomem;

			if (IS_ERR(q))

				goto out;

			br_write_lock(&vfsmount_lock);

			list_add_tail(&q->mnt_list, &res->mnt_list);

			attach_mnt(q, &path);
@@ -1277,7 +1282,7 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, 
		}

	}

	return res;

Enomem:

out:

	if (res) {

		LIST_HEAD(umount_list);

		br_write_lock(&vfsmount_lock);
@@ -1285,9 +1290,11 @@ Enomem: 
		br_write_unlock(&vfsmount_lock);

		release_mounts(&umount_list);

	}

	return NULL;

	return q;

}



/* Caller should check returned pointer for errors */



struct vfsmount *collect_mounts(struct path *path)

{

	struct mount *tree;
@@ -1295,7 +1302,9 @@ struct vfsmount *collect_mounts(struct path *path) 
	tree = copy_tree(real_mount(path->mnt), path->dentry,

			 CL_COPY_ALL | CL_PRIVATE);

	up_write(&namespace_sem);

	return tree ? &tree->mnt : NULL;

	if (IS_ERR(tree))

		return NULL;

	return &tree->mnt;

}



void drop_collected_mounts(struct vfsmount *mnt)
@@ -1590,14 +1599,15 @@ static int do_loopback(struct path *path, char *old_name, 
	if (!check_mnt(real_mount(path->mnt)) || !check_mnt(old))

		goto out2;



	err = -ENOMEM;

	if (recurse)

		mnt = copy_tree(old, old_path.dentry, 0);

	else

		mnt = clone_mnt(old, old_path.dentry, 0);



	if (!mnt)

		goto out2;

	if (IS_ERR(mnt)) {

		err = PTR_ERR(mnt);

		goto out;

	}



	err = graft_tree(mnt, path);

	if (err) {
@@ -2211,10 +2221,10 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, 
	down_write(&namespace_sem);

	/* First pass: copy the tree topology */

	new = copy_tree(old, old->mnt.mnt_root, CL_COPY_ALL | CL_EXPIRE);

	if (!new) {

	if (IS_ERR(new)) {

		up_write(&namespace_sem);

		kfree(new_ns);

		return ERR_PTR(-ENOMEM);

		return ERR_CAST(new);

	}

	new_ns->root = new;

	br_write_lock(&vfsmount_lock);

fs/pnode.c

+3 −2
Original line number Diff line number Diff line
@@ -237,8 +237,9 @@ int propagate_mnt(struct mount *dest_mnt, struct dentry *dest_dentry, 


		source =  get_source(m, prev_dest_mnt, prev_src_mnt, &type);



		if (!(child = copy_tree(source, source->mnt.mnt_root, type))) {

			ret = -ENOMEM;

		child = copy_tree(source, source->mnt.mnt_root, type);

		if (IS_ERR(child)) {

			ret = PTR_ERR(child);

			list_splice(tree_list, tmp_list.prev);

			goto out;

		}

kernel/audit_tree.c

+5 −5
Original line number Diff line number Diff line
@@ -595,7 +595,7 @@ void audit_trim_trees(void) 


		root_mnt = collect_mounts(&path);

		path_put(&path);

		if (!root_mnt)

		if (IS_ERR(root_mnt))

			goto skip_it;



		spin_lock(&hash_lock);
@@ -669,8 +669,8 @@ int audit_add_tree_rule(struct audit_krule *rule) 
		goto Err;

	mnt = collect_mounts(&path);

	path_put(&path);

	if (!mnt) {

		err = -ENOMEM;

	if (IS_ERR(mnt)) {

		err = PTR_ERR(mnt);

		goto Err;

	}
@@ -719,8 +719,8 @@ int audit_tag_tree(char *old, char *new) 
		return err;

	tagged = collect_mounts(&path2);

	path_put(&path2);

	if (!tagged)

		return -ENOMEM;

	if (IS_ERR(tagged))

		return PTR_ERR(tagged);



	err = kern_path(old, 0, &path1);

	if (err) {

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