Function blkcg_policy_register only make sure pd_alloc_fn and pd_free_fn in pairs, so pd_alloc_fn could be NULL in registered blkcg_policy. Check NULL before use for pd_alloc_fn in blkcg_activate_policy to avoid protential NULL dereference. Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxx> --- block/blk-cgroup.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 463c568d3e86..fc083c35dc42 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1404,6 +1404,9 @@ int blkcg_activate_policy(struct request_queue *q, if (blkcg_policy_enabled(q, pol)) return 0; + if (pol->pd_alloc_fn == NULL) + return -EINVAL; + if (queue_is_mq(q)) blk_mq_freeze_queue(q); retry: -- 2.30.0
