[PATCH] cgroup: fix potential null pointer risk

[Shida Zhang]

We previously assumed 'parent' could be null,
so null pointer judgment should be added.

Signed-off-by: Shida Zhang <zhangshida@xxxxxxxxxx>
---
 kernel/cgroup/cgroup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index adb820e98f24..7f230b0ab644 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -5701,7 +5701,8 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 	}
 	spin_unlock_irq(&css_set_lock);
 
-	cgroup1_check_for_release(parent);
+	if (parent)
+		cgroup1_check_for_release(parent);
 
 	cgroup_bpf_offline(cgrp);
 
-- 
2.25.1