cgroup: cgroup_get_from_id() must check the looked-up kn is a directory

cgroup has to be one kernfs dir, otherwise kernel panic is caused, especially cgroup id is provide from userspace.

Ming Lei committed 4 years ago

Commit df024521 parent a81e18e1 file · +4 −1Browse files

Unified · Split

@@ -6049,6 +6049,9 @@ struct cgroup *cgroup_get_from_id(u64 id) · 6048 unmodified lines
6049	6049	if (!kn)
6050	6050	goto out;
6051	6051
	6052	+ if (kernfs_type(kn) != KERNFS_DIR)
	6053	+ goto put;
	6054	+
6052	6055	rcu_read_lock();
6053	6056
6054	6057	cgrp = rcu_dereference((void __rcu __force *)&kn->priv);
@@ -6056,7 +6059,7 @@ struct cgroup *cgroup_get_from_id(u64 id) · 1 unmodified line
6056	6059	cgrp = NULL;
6057	6060
6058	6061	rcu_read_unlock();
6059		−
	6062	+put:
6060	6063	kernfs_put(kn);
6061	6064	out:
6062	6065	return cgrp;