fix cgroup_do_mount() handling of failure exits

same story as with last May fixes in sysfs (7b745a4e40
"unfuck sysfs_mount()"); new_sb is left uninitialized
in case of early errors in kernfs_mount_ns() and papering
over it by treating any error from kernfs_mount_ns() as
equivalent to !new_ns ends up conflating the cases when
objects had never been transferred to a superblock with
ones when that has happened and resulting new superblock
had been dropped.  Easily fixed (same way as in sysfs
case).  Additionally, there's a superblock leak on
kernfs_node_dentry() failure *and* a dentry leak inside
kernfs_node_dentry() itself - the latter on probably
impossible errors, but the former not impossible to trigger
(as the matter of fact, injecting allocation failures
at that point *does* trigger it).

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2019-01-06 11:41:29 -05:00
parent 1c7fc5cbc3
commit 399504e21a
2 changed files with 12 additions and 5 deletions

View file

@ -196,8 +196,10 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
return dentry;
knparent = find_next_ancestor(kn, NULL);
if (WARN_ON(!knparent))
if (WARN_ON(!knparent)) {
dput(dentry);
return ERR_PTR(-EINVAL);
}
do {
struct dentry *dtmp;
@ -206,8 +208,10 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
if (kn == knparent)
return dentry;
kntmp = find_next_ancestor(kn, knparent);
if (WARN_ON(!kntmp))
if (WARN_ON(!kntmp)) {
dput(dentry);
return ERR_PTR(-EINVAL);
}
dtmp = lookup_one_len_unlocked(kntmp->name, dentry,
strlen(kntmp->name));
dput(dentry);