[PATCH 5.19 164/207] cgroup: cgroup_get_from_id() must check the looked-up kn is a directory

Greg Kroah-Hartman
2022-09-26T11:56:34Z

From: Ming Lei <ming.lei@redhat.com>

commit df02452f3df069a59bc9e69c84435bf115cb6e37 upstream.

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

Reported-by: Marco Patalano <mpatalan@redhat.com>
Fixes: 6b658c4863c1 ("scsi: cgroup: Add cgroup_get_from_id()")
Cc: Muneendra <muneendra.kumar@broadcom.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: stable@vger.kernel.org # v5.14+
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/cgroup/cgroup.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6026,6 +6026,9 @@ struct cgroup *cgroup_get_from_id(u64 id
if (!kn)
goto out;

+ if (kernfs_type(kn) != KERNFS_DIR)
+ goto put;
+
rcu_read_lock();

cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
@@ -6033,7 +6036,7 @@ struct cgroup *cgroup_get_from_id(u64 id
cgrp = NULL;

rcu_read_unlock();
-
+put:
kernfs_put(kn);
out:
return cgrp;