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: David Howells <dhowells@redhat.com>
Cc: Valerie Aurora <valerie.aurora@gmail.com>
Cc: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index 8f412ab..be1b07a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -708,56 +708,60 @@
int flag)
{
struct super_block *sb = old->mnt.mnt_sb;
- struct mount *mnt = alloc_vfsmnt(old->mnt_devname);
+ struct mount *mnt;
+ int err;
- 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;
+ mnt = alloc_vfsmnt(old->mnt_devname);
+ if (!mnt)
+ return ERR_PTR(-ENOMEM);
- if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
- int err = mnt_alloc_group_id(mnt);
- if (err)
- goto out_free;
- }
+ 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;
- mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
- atomic_inc(&sb->s_active);
- mnt->mnt.mnt_sb = sb;
- mnt->mnt.mnt_root = dget(root);
- mnt->mnt_mountpoint = mnt->mnt.mnt_root;
- mnt->mnt_parent = mnt;
- br_write_lock(&vfsmount_lock);
- list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
- br_write_unlock(&vfsmount_lock);
-
- if (flag & CL_SLAVE) {
- list_add(&mnt->mnt_slave, &old->mnt_slave_list);
- mnt->mnt_master = old;
- CLEAR_MNT_SHARED(mnt);
- } else if (!(flag & CL_PRIVATE)) {
- if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
- list_add(&mnt->mnt_share, &old->mnt_share);
- if (IS_MNT_SLAVE(old))
- list_add(&mnt->mnt_slave, &old->mnt_slave);
- mnt->mnt_master = old->mnt_master;
- }
- if (flag & CL_MAKE_SHARED)
- set_mnt_shared(mnt);
-
- /* stick the duplicate mount on the same expiry list
- * as the original if that was on one */
- if (flag & CL_EXPIRE) {
- if (!list_empty(&old->mnt_expire))
- list_add(&mnt->mnt_expire, &old->mnt_expire);
- }
+ if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
+ err = mnt_alloc_group_id(mnt);
+ if (err)
+ goto out_free;
}
+
+ mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
+ atomic_inc(&sb->s_active);
+ mnt->mnt.mnt_sb = sb;
+ mnt->mnt.mnt_root = dget(root);
+ mnt->mnt_mountpoint = mnt->mnt.mnt_root;
+ mnt->mnt_parent = mnt;
+ br_write_lock(&vfsmount_lock);
+ list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
+ br_write_unlock(&vfsmount_lock);
+
+ if (flag & CL_SLAVE) {
+ list_add(&mnt->mnt_slave, &old->mnt_slave_list);
+ mnt->mnt_master = old;
+ CLEAR_MNT_SHARED(mnt);
+ } else if (!(flag & CL_PRIVATE)) {
+ if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
+ list_add(&mnt->mnt_share, &old->mnt_share);
+ if (IS_MNT_SLAVE(old))
+ list_add(&mnt->mnt_slave, &old->mnt_slave);
+ mnt->mnt_master = old->mnt_master;
+ }
+ if (flag & CL_MAKE_SHARED)
+ set_mnt_shared(mnt);
+
+ /* stick the duplicate mount on the same expiry list
+ * as the original if that was on one */
+ if (flag & CL_EXPIRE) {
+ 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 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 @@
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 @@
}
}
return res;
-Enomem:
+out:
if (res) {
LIST_HEAD(umount_list);
br_write_lock(&vfsmount_lock);
@@ -1285,9 +1290,11 @@
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 @@
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 @@
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 @@
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);
