[PATCH 5.15 06/83] cgroup: cgroup_get_from_id() must check the looked-up kn is a directory

[Greg Kroah-Hartman]

From: Ming Lei <ming.lei@xxxxxxxxxx>

[ Upstream commit df02452f3df069a59bc9e69c84435bf115cb6e37 ]

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

Reported-by: Marco Patalano <mpatalan@xxxxxxxxxx>
Fixes: 6b658c4863c1 ("scsi: cgroup: Add cgroup_get_from_id()")
Cc: Muneendra <muneendra.kumar@xxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Acked-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.14+
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 kernel/cgroup/cgroup.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 97282d6b5d18..4b19f7fc4deb 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6025,6 +6025,9 @@ 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);
@@ -6032,7 +6035,7 @@ struct cgroup *cgroup_get_from_id(u64 id)
 		cgrp = NULL;
 
 	rcu_read_unlock();
-
+put:
 	kernfs_put(kn);
 out:
 	return cgrp;
-- 
2.35.1