Hi, Tejun
在 2022/10/11 4:29, Tejun Heo 写道:
On Mon, Oct 10, 2022 at 10:38:58AM +0800, Kemeng Shi wrote:
Function 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;
This isn't the only place this function is called, so the above won't
achieve much. Given that this is rather trivially noticeable and all the
current users do implement pd_alloc_fn, I'm not sure we need to update this
now.
It's right all the current users implement pd_alloc_fn, can we check
pd_alloc/free_fn NULL instead in blkcg_policy_register()?
Thanks,
Kuai
Thanks.
